FWIW, if there were to be such a thing as a 20' long railroad tie, I'd have no problem walking it from end to end. Put that same tie 100 feet in the air and I'd surely fall off and kill myself. The mind plays tricks.
I have no doubt, from a scientific viewpoint, that the pull-out strength, in an aluminum casting, of four carb studs is several times the weight of an FE engine complete with a C6 trans attached. But the idea of using a carb plate still makes me uneasy.
I use a chain attached to the engine/trans in such a way that it can be picked up at enough of an angle to put the whole thing in at one time. Manually lift the tailshaft housing over the rad support and it'll slide right in with ease. Use a small floor jack, positioned to hold the back end of the trans, and let it roll back into position as the engine is lowered.
(And, by the way, an FE isn't really a 'Heavy dog'. An FE, with the usual aluminum acoutrements, actually weighs less than an all-iron small block.)
KS