Mazolini first 417 C.I. B1 motor was bought from Koffels which had been in there Comp eliminator car, it was a KB block with 4.5 bore and a stroke short enough to make that C.I.. He put in his 1964 Savoy SS car to make it into a SS/BM, he would shift it right at 8600 RPM, if he miss the shift by 150 RPM it would pull one or more of the 5/16 bolts that held the T&D rocker stands out
His second motor had a set of B1-MC heads on it and it was smaller, 411 C.I. I think he still has that motor
Short stroke, large bore, big heads