Pump the brakes lol.

-130k miles, it won't need a rebuild. You might end up doing more harm than good.
-243 heads will lower compression, you'll lose only a little bit of power, but a fair amount of torque.
-Skip OEM cams. Get a real cam that will make the power curve you need.
-The 4L60e isn't a very good trans. They have several problems. Also, you would need a standalone that can do transmission control.
-A stock 4L80e will outlast any mild built 4l60e.
-FITech system is like a self-adjust carb. They're not the most ideal. For something you don't want to mess with, they will work fine.

 

 

The FITech manifold loses power/torque everywhere below 6000 RPM compared to a stock 5.3 truck manifold. Not to mention, the FITech is geared towards ease of use and safety and shys away from optimal power/torque. In a 6000 lb vehicle, expect it to be a dog.

 

Thanks for that info i was wondering about there system. i have the factory system still so it will work. there is a tuner in Spokane that ca make me a stand alone system . i have lots to think about for the 5.3 got a suggestion for a cam, for my application. Thanks for your help But i do like the cool looking manifold FI has lol

 

Gen 4 truck intake is going to be your best bet for power/torque on a budget that still makes excellent cruise/pulling torque.
Up to 4000 RPM, it makes more torque than most aftermarket manifolds as well.

Stock PCM/harness will do what you want. If you're going to spend the money, the Holley does trans control as well.

The FITech manifold is the same Chinese manifold that over 30 companies claim to be their own.
They are riddled with issues. They make poor torque and are noisy. Some people have even had them come apart.

 

 

JoeNova gave you solid advice so there isn't much left to add to this except I would go for a drop in truck cam. They add power but they don't trade off low end torque like most cams and you're gonna need as much torque as you can get. A small stall (torque converter) would be a good idea also, something around a 2500-3000 stall. You could go bigger too, but a stall will help with rock crawling since they multiply torque and will give you that flash of low end power you need.

 

 

 

^^^^^^This. Especially FITech or Megasquirt. If you MUST go standalone, use Holley's. It is good stuff. But OEM will do the job for most (90% +) applications.

 

 

I'm going to also say that your idea of running a 4L60E should be revisited. They are exceptionally weak units with known issues with the planetaries, output shaft, aluminum input drum, sunshell, input sprag, insufficient internal space for increased friction surface area, and many, many, other weaknesses. You can also expect transmission case life to be very short if you plan on offroading with larger tires. The center support in that unit will damage the cast in case lugs requiring upgrades to address it, or case replacement. You would be far better served by starting with any other transmission except the 700R4/4L60/4L60E family. You can WASTE a bunch of money trying to "beef one up" but in the end, after spending thousands of dollars, you will still have a transmission that is far weaker than an all stock 4L80E.. If you don't do much freeway driving, you could also use a 3 speed trans such as the TH-350, or TH-400. Both of those in stock form are significantly stronger than a 700/60E is, or could ever be.. If you use the TH-350 you will find that it is shorter in length and this will allow you to run a driveshaft that is a little longer in the rear. Using an 80E is going to have you using a very short rear driveshaft.. So short that the angles will eat up U-joints. You can expect that you will be changing U-joints out on a fairly regular basis if you drive the vehicle a significant amount of miles.

 

He needs low, end. The LS1 cam will lose low end in exchange for high end so I wouldn't use that cam. There's tons of threads where guys put LS1/LS6 cams in trucks and hated it.

I'd call BTR (brian tooley racing) or Cam Motion for your cam setup.

Good advice.

 

 

 

So those gears and tires get you around 24.4" inches per driveshaft revolution, which gives you a final drive ratio similar to a fullsize silverado 1500 with 31" tires and 3:73 gears. If you do a search on the old google machine you'll see alot of folks do tow trailers with the particular combo you have (5.3 and 4L60E in various platforms IE pickups, tahoes, surburbans etc) and they mention time and time again in towing applications (which is what I would presume your application is the closest to vs drag racing) temps kill these things particularly fluid temps in the 230+ range. As long as the transmission and transfer case are in good shape you should be fine, but again keep heat out of it. What I'm more curious about is are you running the OEM transfer case and if so how do you plan to activate the transfer case given I believe most if not all of them by that time are electronic.

Again as for your motor you don't need to do a full rebuild on it to get 385 hp, in fact I'd be tempted to run it as is. Stock they are rated for 275-285. While I have never dynoed a 5.3 if they are anything like the 5.7 HP wise they are probably closer in reality to 300. If you didn't know GM when the LS platform came out was known to have a large number of factory freaks running around, particularly in the 5.7 motors. In short there were plenty of 5.7 fbodies which should have been making 260-275 at the wheels stock that were actually making 300ish if not more. Timesheets backed up these numbers with some bone stock cars running low 13's to high 12's in the quarter mile STOCK trapping well over 105 mph. So I wouldn't get too wrapped up in doing alot of work to it if it runs ok now.

 

Those 5.7 F bodies that had "extra" power had LS6's in them. Apparently GM ran short of LS1's, so they dropped LS6's in their place! Build cost difference was minimal, so GM didn't lose much on the deal.