Actually, all you need to do is locate a 400 crank and 400 pistons. That will drop into your 351M and make it a 400. The best cams for the 335 series Fords are the Comp Cams 255, 265 or 275 grinds. They are dual pattern and these engines love em. Check out my gallery for pics of my 400 (402 actual) bored out to a 410. I'm getting about 365 Hp and over 400 ftlbs of torque. I'm running a Ford SVO cam, though.