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.
Is the bore different between 318and 360 or just the stroke? If you're having it honed anyway maybe it doesn't matter. Have a 318 block I'll sell you cheap...