5.0 gods! quick question, need your help!

The stock 86 pistons do not have reliefs cut in them, so he will have to mock them up to be sure with out notching, with out reliefs that cam will not work....

Yup no valve reliefs in the pistons means that lift is limited. I would say slap the E7's on there and leave the stock cam...always check PV clearance.

The pistons are 'flat-topped', and the 4 valve reliefs were not on the pistons until 87+...

The heads shouldn't be an issue, I don't recall the valve size is that much different...but as for the cam, I would suggest not doing that

He needs to swap out the bottomend with a rebuild with pistons with valve reliefs, so he can see benefits later or otherwise he will probably hit a plateau eventually

actually the heads may very well be an issue. More times than not, e7 heads won't work with an 86 block. I've had two friends personally try unsuccessfully. I'd just pull the motor and swap it with an 87+ block, it's about the same amount of work as what you're going to undertake anyhow....do you really want to rip it all apart just to find that it won't work? My .02

as for the 86 cam, I'm not a huge fan of that either. It's a stock cam, but it will work great with the e7 heads. If you upgrade to gt40 heads or ported e7's, ditch that stock pos cam in a hurry. My bro and I built essentially identical combo's.....both 86 mustangs with gt40 headed motors. the difference was that I kept the 86 cam, and he went with a tfs 1 cam. His car has about the same amount of torque (No seat of the pants difference),.....however my car quits making power maybe 5400/5500 TOPS, and his car makes power and pulls like a mother all the way to 6 grand.

there should be some casting #'s on the block near where the starter goes.

Man, this guy won't give up eh?! Let him learn on his own. There is a reason I ditched that block for one with dished pistons. Why would you want to limit yourself?