joe you can use gm oval big ports they will do the job but when building up a engine combo look at what rpm you will you be at ?here some things to think about if you use a 454 crank and a 250 long rod and a 427 piston you can go from a 427 to 454 with a longer rod and this can be done cheap and get it zero deck if its a good block they can go 0.60 or 100 . for cam a roller 720lift I 270 @0.50 EX 278 on 108 if you run in mud you can get this stuff use on e bay like the cam intake but buy the piston new and the roller lifters new I hope this helps. if you bore this thing out .100 i would short fill it with block rock