Critique my mismatched Teen Build.

Engine recipe looks good. Think twice about going bigger on the cam. Big cams like big compression. Go too far and throttle response drops off. Comp Cams has selection free software available. http://www.compcams.com

Agree with recommendation for dumping the 7¼ axle and its 2.92 ratio. If you are unable to find a Mopar 8¼ or 8.75, suggest looking at first and second generation (1960-72, Australian) Falcons for a 9" or maybe an 8.8". The spring perch width should be the same as your A-body. The five-bolt wheel axles match BBP Mopar. Suggest a 3.55:1 ratio with a locking diff.