yeah think ur right, mfi head wont fit lean burn, think piston tops are different design as far as im aware. u any closer to puttin the cam in?? am really intreaged to c wat a difference that will make. when i first built up my engine i was usin a high lift cam i got from an xr3i i broke, but coudlnt get her to run, fueling probs mainly. also couldnt ID the cam which nvr helped tryin to set up timing either!!! not a big deal to change tho, was worth a shot.