Blocks and internals the same?

It will be street motor that will run the 1/8th everyonce in a while. Probably around 275 hp. The trannny is a 727 soon to be a forward pattern manual, around 2800 stall, rear end will either be 3:55 or 3:91 geared 8 3/4 that came out of my 72 demon Its my sons car and he still has to be able to drive it to school. I have an LD340 intake and was thinking of using J heads ported and gasket matched and everything I know to do to them. Ive done a set of 906's on 400 that ran mid 12's in my 69 charger that still run on pump gas. Headers are 1 5/8" Doug Thorley and will put a complete 3" with flowmasters. I have 650 double pumper List #4777-4 that we will use for now. Thanks any info will be helpful. Oh by the are both cranks cast?
This car was a 31,000 mile 1 owner car when I bought it for my son and still looks almost new.