G'day fellas, have built a S&S 107 in my breakout, 1.9 intake Valves Ported polished heads, behive springs. Throttle body, s&s lifters + push rods, S&S oil pump and cam plate.

Hi mate it sort of depends where you want the power, like down low, mid or up high in the rev's- here's a couple of Dyno charts from Fuelmoto- https://university.fuelmotousa.com/dyno-charts/

Do you know what your compression is mate? What don't you like about the MR103's?

As Hilly say what Comp you running . If 10. 5 a inlet closing at 46 deg . but then what is your springs PSI and max lift ? roller rockers ?