what needs to be changed in a 72 340 to be like a 70 340?

Hmm, well I never timed it after the switch and had not so long before the rod went out. Just a few months.

They were cheap 1 5/8 Headman headers. Hooker Super Comps likely would have flowed better.

I have hear of the BB boys running even in to the 10's still using some type of factory cast manifold. But they make stroker kits for those motors too.