I have a 383 in the works with similar parts(Scat stroker crank,Mahle flat tops, Scat 6" rods).
I have Alum heads that have about 72cc chambers, and with the flat tops 5cc, and with a .039 squish I get about 10.3:1 static CR. Looking to get a roller cam with about 270-276 adv. duration to get less than 8.5:1 dynamic CR for pump gas on the street. IMO if you get 64cc heads your CR is going to be too high for pump gas, and you'll regret it.
If your pistons have the same 5cc reliefs mine do, I'd get some heads with at least 72cc chambers if you plan to use a stock convertor auto trans on the street.
Also I heard some bad things about the Professional Products dampners (after I bought mine of course). The timing numbers are painted on and I wouldn't expect them to be very visible for more than a few years before they seccumb to the elements. IMO, and many others, Powerbond makes a better dampner, but you can't get it from Summit if I'm not mistaken. I got mine from O'Reilly Auto Parts. The numbers are engraved, and painted. If they get indescernible you can fill them back up with paint with a little effort. Also supposed to have a better elastomer bond.
I also have the Air Gap manifold, but welded up the plenum divider notch in hope of smoother idle and better off idle instantaneous throttle response. Keeping fingers crossed. I would probally have bought the regular RPM instead of Air Gap had I known that it had a notch beforehand.
Using a Felpro 1010 Head gasket w/copper combustion ring for Alum. heads. Ported intakes to match a Felpro 1205, exhaust to mate with a Felpro 1406, and Tri-Y headers.
Using a 750 Holley with a 1/4" 4-hole insulator/gasket/adapter. The adapter is mainly because I couldn't get a manifold vacuum fitting to fit under the Holley without one.
I'm hoping for about 425-450hp and 475ftlbs of torque. It looks as if your going for more horsepower than torque like me, but keep us posted as to how things turn out. I for one am very interested.