11:1 with a flat top and tight quench is doable with an aluminum head.
my friend's LT1 stroker is at about 11.75:1 with a [Email]230@.050[/Email] (280 adv) hydraulic roller....granted it's got reverse cooling and computerized spark control.
as long as you don't get overly aggressive with your mechanical advance & vacuum advance curve, I think you'll be OK with 11ish:1 compression
BTW the eddie heads you want are the 63cc closed chamber, not the 65cc open chamber heads. to be on the safe side you could polish the chambers and round any sharp edges in the chambers and tops of the pistons. that'll help with detonation, plus it'll increase the chamber volume a few cc's...
also, a head gasket with a smaller bore may be better, if there's an off the shelf one (say a 4.06 bore) in the proper thickness to minimize the crevice volume.
go to keith black's website (kb-silvolite.com) and play around with the dynamic compression calculator. read up on this thread:
https://board.moparts.org/ubbthreads/show...e=0#Post4885314and play with the calculator, shooting for about 8.2-8.5DCR.
if you do run into detonation, a cam with slightly more duration will bleed more cyl. pressure out, helping things. conversely, you could also just retard your cam a couple of degrees with an offset cam key to make the intake closing point further after BDC (same thing more duration does)