dont do it! look at the upper right of the pistons in the pic and you can see the mark from the valve. this was with GT40p heads and a small cam. it really shouldnt have happened but it DID. Get some new pistons! damn flat top pistons.
Most people were fortunate to do this swap some were not. I know alot of people have had success with the E7's but not sure about cams. Gotta be real careful when choosing a cam with E7's on an '86 short blcok especially if it's still Speed Density. Check out www.corral.net and search the forums about the headswap, I've read alot of helpful info about this. Good luck.
with a stock ho cam its about .030 to .040 clearance with older heads that have the same valve placements as e7's the e6 head the valves are .100 higher into the head