Mercury's 383 stroker motor's were designed to replace 7.4L/8.1L. Factory warranty and support. Plug and play. I used the 357 version to replace a 7.4L in a Sea Ray with a Bravo 1 and it used the same prop and only lost 100 RPM. Used less fuel though. You can build your own, buy a something like the Summit one but I have to say Merc did thier homework on the cam profile as this thing makes the torque and horsepower to replace a big block Chevy.