Rumble, i've done a few of the A body BB swaps over the years., its relatively easy, but i will say, if you just drop in a run of the mill rebuilt BB with a stock bottom end, you won't be that happy with it, there basically plagued with the same issues the SBs have, lack of compression/cam/exhaust ect., so if you decide on just a rebuilt BB, change the pistons, & don't skimped to much on a cam, BBs love bigger cams.