It's time to put the motor in the 99 ss
 

What kinda shop or work space do you have? Having a lift vs doing it on the ground can sway the decision possibly.

I'd do it from the bottom. Roll the K member all assembled under it, while having the car lifted up w/ the engine hoist.

This is the procedure I used when I did mine. It was a huge help. You don't need a car lift, just a way to lift the front end of the car with the engine hoist. I took a 6ft tow strap, went around the radiator support and lifted it that way. You can also look up videos on youtube to get an idea of how people do it. Just watch how they pulled it, and reverse it to go back in. After pulling engines, I decided to drop the front end out of a 4th gen, it is way easier since the engine is seated so far back under the cowl. There are some who do prefer to go from the top though, both ways have been talked about on here a lot, just do some searching and decide what will work best for you.

https://ls1tech.com/forums/general-m...ls1-fbody.html

If you have the means and confidence, go from the bottom. You can have the engine more put together and ready to go that way. Trans matted up, exhaust bolted up etc.

Just off the top of my head...and I will forget some things...
Disconnect the harness connections that run through the firewall (behind PCM) and connect to the BCM. Unbolt/unclip the PCM. Undo the harness connections on the passenger side shock tower (C100, starter wire, etc.) Unbolt the two front brake lines from the abs block and undo the bracket holding the lines to the chassis. Remove both front wheels, undo the wheel speed sensor and unclip the sensors from the chassis. Unbolt the shocks from the top of the shock towers (2 hex bolts, two torx bolts). Undo the battery harness from the battery, unbolt the passenger side ground to chassis, unbolt the driver side power feed to fuse block assembly, undo the little braided chassis ground on the driver side. Undo the coolant lines going to the engine. Remove the intake connected to the MAF. Undo the brake booster hose from the brake booster. Undo the throttle cable. Remove the driveshaft, the exhaust y-pipe. Undo the front sway bar mounting brackets from chassis. Undo the torque arm mount from the tail of the transmission. For a manual car you will have remove the center console to access the shifter for removal. For an automatic car you will have to undo the shifter cable bracket from the bottom of the pan, also there may be a breather hose that goes from the top of the trans and clips to the torque arm, you'll have to undo that. Finally with the car chassis properly supported, remove the 6 k-member bolts and the 4 transmission crossmember bolts. It sounds like a lot to do, but it really isn't once you start getting your hands dirty. When you are dropping the engine, pile the PCM and harness and anything else on top of the engine and pay close attention when raising the body so make sure that nothing snags or breaks. Just go slow and steady and you'll be alright. Once you have done it completely, you'll never want to remove the engine from the top again, at least that's how I feel now that I have done it many times.

Way easier out the top, just pull the passenger side pedestal, four bolt and it will clear the bellhousing how I did it in a few hours..

I did this in my driveway by myself with just a floor jack, some jack stands, and an engine hoist--and a couple of dollies under the engine. It is really easy to insert from below. I am assuming you already have the engine sitting in the K-member.

-Connect the engine to the trans outside the car, you'll be happy you did this later. Also headers.
-Leave off the alternator
-Lift the nose with the engine hoist by grabbing the lower hood latch point.
-Slide engine under
-Rest car level on jack stands
-Loosen the brake lines below the ABS block if any are in the way or reconnect them later if they were already pulled with the K-member.
-Position the jack below the oil pan with something flat so that it does not rest on the 4 fingers.
-Align the engine as close as you can below the bolt holes.
-Adjust the center of gravity by moving the jack around underneath the oil pan until it lifts mostly balanced. If it is crooked, go back down and try again in a new spot. Take your time.
-Lift the engine up and see how close it is to being aligned. If you are way off, start back on the previous step.
-Lift the engine up part way and reconnect all the main harness grounds at the back of the driver side head. There are 2 bolts with 5 grounds or something like that. They are really hard to reach once the engine is all the way in.
-Plug in any sensors at the back of the engine.
-Remember to keep an eye on the upper shock mounts as you lift.
-Lift the engine the full way up until the K-member meets the chassis. If you are close enough, it will align itself.
-Start threading each of the 6 big bolts into the K-member by hand.
-Tighten bolts
-Engine in! Connect everything else...