new from the uk

Welcome to the site George. Good luck with your project.

To answer a few of your questions........

Looks like you have a 1972 360. My sources show it was rated at 175hp @ 4000 rpm's and the torque was 285 @ 2400. These are net ratings, so appear a little lower then you might think. Similar gross ratings were 255hp & 360tq.

The "915" heads are also known as the "J" head. They are large port and the factory valve sizes were 1.88 int & 1.60 exhaust. Most will cc the chamber volume in the low 70's.

True compression on these engines is around 8.0 to 1.

A good exhaust, dual plane intake and a small (600ish) carb, along with a good timing curve, will wake it up nicely. Just use caution when upgrading the cam to not go too big on intake duration as that will lower the already low cylinder pressure.