Newbie (sort of) needs some ideas...

If you use a pre '68 crank,you can keep the small pilot. All 225 are the same from 60-75,with the exception of the change in pilot bushing size. So you can mix and match blocks/cranks/heads. The 5 freeze plug BH block is the strongest(I think they made them 1969+)but for what you want,you can run any block. All slants pre 76 are forged crank motors. You will want a head with the revised combustion chambers,which is 68+ (but some 67's had it,my old 67 Dart GT did)search slantsix.org for the casting number for this head.If you want a nice driver with a mild cam and small 4 bbl go with the offy intake. If you want to run a big cam/carb,port the head and run high comp. run the clifford.