I am currently building a 87 tII rx7 with a GM 3800 and t5 from a 2000 Camaro. Its not a bone stock motor, it does have a mild cam, the intakes are port matched, and the balance shaft is deleted.
I know its not a LS engine, but I am not looking to build such a brutal car this time around. I am wanting reliability, manual tranny, good gas mileage, air conditioning(Texas summers are hot and humid), and a once and a while track car.
So I picked up a 2000 camaro 5 speed with a bad differential for $400. I then sold the bumpers, lights, seats and a few other interior pieces. This paid me all my money back and paid for most of the build so far.
So first I tore the motor down and checked it out, it was in great shape and seemed to be a recent rebuild. The only issue I could find was tons of carbon on the valves and pistons. I put in a new cam and stronger valve springs.
Next was test fitting and placement of the engine. I placed it as far back and down as I could get it without having to cut or reshape anything. I made my own engine mounts as no one sells a kit. Even if they did I would still have made my own. $18 in materials and 4-5 hours time, compared to a lot of these companies that are asking hundreds or even some cases thousands for a couple of welded chucks of metal.

Test fitting the engine and trans.

engine and transmission mounted with wire mess started

set of pace setter headers arrived

headers are modified to clear the body and steering shaft. Accessories are mounted, belt installed, fuel pump is wired, etc...... engine is able to be started and idles nicely at this point.

custom driveshaft built and picked up.