Ok, I might get chewed here, I might not. To start with. I have a 72 1200 sedan shell, with a L20b and 5 speed strapped into its bay( tunnel cut out) I bought it like this.
I own 2 spare a12s, and 3 4 Speed gear boxes.

I am looking at making the sedan, a beginner circuit/ hill climb car. Maybe even put it on the roads for a bit.
The question is what is an ideal set up to begin working towards.