[KTL]

You shouldn't have any problems with piston-to-valve clearance because the JE pistons have sizeable valve reliefs cut in them. But the cams are designed to work with original Porsche pistons and even those don't have issues with valve clearance.

I don't think you'll have emissions issues because the cam is certainly a bit more aggressive in terms of duration and lift (especially more peak lift on exhaust) but the lobe center is a still a "smog cam" in the 112-113 range.