both are great engine builders.
i have a passion bike is its a beast,by my thoughts,
ive seen jeff bikes in action, they are beast also. basically its a toss up.
both guys are beyond nice and really knowledgeful.
so its your personnal opinion, either way you wont get screwed.
if you choose a passion +4 stroker, i can get you really close on the jetting.
also i would suggest the cpi or shearers on both motors. my bike as plenty of low end with shearers. and a kick ass top
best of luck, whatever you choose you wont be unsatified.