i say go for it. b bodies and b motors go together like pb and jelly. i think in 72 all the v8 k-members are the same except for hemis so all you will need is mounts, bb tranny and driveshaft...and prob a radiator.if you plan on putting the engine in as is, at least put a new timing chain set in. sure the compression may be less than 8:1 but a stock 400 with 4v and a mild cam will be night and day compared to the 318 you have now. put it in, have fun and save your money to build a killer motor for later.