Engine and tranny help for novice pure stock racing

First, lose the 727. A 904 is lighter and takes a lot less power to drive. In addition, the convertors are lighter too.
On the cam - If it has to be stock replacement, the lift rule doesnt matter. I would stick a set of Magnum heads on it to get the 1.6 ratio rockers, and run the '68 340 4sp cam.