Scored A Set Of Magnum R/T's!!!!!
No need to go .060 over. The amount of cubes and resulting HP is minimal at best. Just clean up the bores or go .030 if you must and build accordingly.
HP levels can be ruffly guesstamated (LOL) by a basic CFM X's 2. While this is a laymans formula, it is good enuff to invision the possibility.
Due note that the MoPar has a few advantages over a Chevy engine that the cry over not having or pay dearly to get. Remember that the real key for any engine and/or car is power to weight ratio and suspension to get going.
Considering this head is on a 318, even in stock form, the R/T heads should be able to make some seriously killer power on the 318 whilest out roaming the street. I do not think you'll need to port them at all.