Magnum blocks

The main advantage is you can find good shape running Magnum fairly easy and they have a bit more cr and the stock magnum head responded well to cam 4bbl and headers. Once you start talking rebuilding the advantages start going away any 360 becomes a good candidate especially if hydraulic roller cam ain't a requirement.

I've heard of the 0.20" overbore limit never heard of anyone having a problem doing the standard 0.30-0.040" overbore.