Mike,
You should be able to find a 390 block pretty easy. The 427 may be a different story as there just weren't that many to begin with. But you can make the 390 into a 427 easy enough, just won't be a side oiler. The 1962/63 406 blocks are good ones too if you can locate one. Once you get the engine built, all you need is a lawn mower to put it on.
Ron
