I pulled & installed Pontiac engines, with TH400 trans bolted to 'em, many times, in our 1st gen drag cars. The 1st few times, the TH400 was actually a long tail.

But, I always had the car jacked up off the floor, so there'd be plenty of room to not only install engine/trans, but to also install headers. So, if I can do it, anybody can.

When I 1st did it, it was the very first time I had installed a Pontiac engine in anything. I was not a good, experienced mechanic, at all. Everything for me was sort of "trial & error", with lots of emphasis on "error".