I already spent a year completely custom-rebuilding a near-cherry Rex, with the 3.8L L36 V6 from a 96 Camaro, the T5 from a 94 Camaro, an FC IFS, my own big brake upgrade with used Mercedes/Brembo 4-piston front calipers, the rear axle housing from a 94 S-Blazer, shafts from a couple of Bronco-2s, posi from a 94 Z28, and 2.29 gears. I had to splice the FB and FC steering columns, adapt the GM P/S to the Mazda rack, new radiator from Summit, new exhaust, new fuel system, new paint, new audio, the list is nearly as long as the build thread.
The back-sback-story is my now-retired mom once had an early 70s Olds Omega she bought new, and loved, and didn't love her 09 Pontiac G3. So the plan was to build something comfy, sporty, and capable of spiking 50 mpg occasionally. My dad had had a 96 Bonneville that did 35 mpg highway with the converter lockup not working. So i knew the L36 had potential.
A year later the car is built, drives great, everything is really well integrated, handling is predictable, cornering and braking power are both extremely good, acceleration is surprisingly strong, but she doesn't enjoy driving it. Now after nearly another year, evdn after dropping the orice incrementally down to $4000, it still hasn't sold.
I have an 01 4.8L LR4, and it is going into this Rex. Not new, others have done it.
I ordered a used bellhousing off ebay that wasn't as advertised, so now i gotta find another one, and not a $270 new casting.
I also ordered a used LS4 intake manifold with fuel rails.
I already fabricated my own mild steel oil pan for this engine, and i plan to use that if possible.
I have a set of 2.73 gears i plan to swap in, until it breaks that 3.75:1 first gear, so there will be a reason to swap a 2.95-first gearset.
The first time through, i put 225/60R15s on 7s on the rear, which i needed for my 86 Camaro, and are now going on her 90 735i.
I had her order a new set of 205/50R15s, and even though she knows I'm all about wide treads, she ordered the narrowest 205s on the planet.
This time i want at least 225/45s up front, and probably try 245s on 8s on the rear. Unless i get a set of fender flares, then 245/40s on 10s up front, and 275/35s on 10s out back.
The heads are ported, the cam is from an 04 LS1, the exhaust manifolds are 98 Z28 pieces, the TB is ported, I guess power should be around 350 HP.
I have a Sachs NFW1050 flywheel, butcan't find the long bolts for it for less than $80/set, can't find an aluminum block for less than 900 for the bare block, and the cost of this junk is unreasonable.
I got a 98 Vortec 454 to blow-through for my 86 Camaro, so the 4.8 needs a home where its non-turbo output will be more than adequate, here it is. I wish i could afford to try a Comp 54-408-11 in this, but unless someone offers me a used one for less than a Benjamin, i have no hope.
The V6 build passed emissions, with dual 2s into a single 2.5, i hope to reuse the 2.5 for the right side of the 4.8L
Pics when i get the hood open.

 

I didn't know the LS4 intske manifold is choked just behind a specific TB, i assumed both to be the same as LS1 spec. I think what i will do id go ahead and cut through the choke point, port it until i can slide in a length of 3" exhaust tubing, then epoxy that in. Should get it breathing like a real LS1 intake. As for the TB, i will probably have to fab my own adapter. There are adapter spacers for LS4 TB to LS1 / LS6 IM, but not vice versa, and my budget is tight.
So over the winter i will tackle that, finish porting my heads, and get the long block reassembled. I'm just going to start with my 4L80E, forget the T5. The T5 will go behind my 3.4L in my LoCost. I'm trading my 98 Vortec 7400 for a divorced NP205 for my 87 S-10, so I no longer need my 4L80E for that 454.

 

So i was thinking if i just got a 3/8" plate of aluminum, and cut a 3" hole, i could drill and tap it for my '01 LM7 TB, drill it to match the LS4 TB, and be good to go. But on studying it some more, maybe I could just cut the plastic TB flange off entirely, and weld a 1/4" mild steel plate to the 3" tube, then drill and tap that instead. Should reduce the risk of leaks, give me more freedom in placing the TB, and make it easier to make a way to keep EGR.
Since I have no flexplate, it seems better to start with an SFI-approved one, even if the SFI certification expires, just to have the strength advantage of it being thicker than stock, and to reduce the labor of swapping one in later, in case it gets a turbo eventually.