360 block to start with?????

Consider a brand new long or short block from World or Mopar. What you save in machine work and don't have to worry about an old engines history of abuse will balance out. Plus the new castings are improved and the metallurgy is superior. New is cheap insurance. I think a Mopart Magnum stroker crate engine might even be better still, although not as fun as building your own.

The magnum crate shortblock is a pretty good shortblock to start with.
The 406 is a good one to work with. There's a dealer local to me who always keeps them in stock among many other mopar performance parts.