A dozen years or so ago, I built a similar engine for my son's Scamp. Used the templates to port the Magnums. That engine ran great. First outings at the track netted 8.10s. I always wished I had put a little more converter and a little more cam in it. Mid to upper 7s would have been easy. And the thing idled and drove like a stock 318. What a great combo. Good luck with yours.

P.S. Get the templates. Don't shoot blind. Improvements are not necessarily intuitive.