Question for those that swapped a big block into their A body.

What were the biggest things/problems you had to overcome to do the swap? I'm up in the air as to whether I want to do the swap (got a line on a 400) or go with a 360.
soooooo, what are you gonna do?
another thought is to use an aftermarket K member that eliminates the torsion bars, like the one HemiDenny makes -- HemiDenny