My guess is that between an M1, Excellerator, and Victor , with all ported/ port matched, and installed on a cookie cutter 500/550 horse bracket stroker motor, the ET difference between all of them would be negligible, at most 1/2 a tenth.
I never seen or touched an Excellerator and would like to but if that’s what was on your old engine they work well. So I agree any of the above with a little tender loving care.
