Thanks for the replies. So it seems that especially with aluminum heads, 9.5:1 is somewhat conservative. Thinking back, my Mustang Mach 1 (351C) had TRW forged pistons- supposedly between 10.5 and 10.7:1, but leaded gas was still available then.
It has been 15 years since I sold it, but I don't recall any detonation or pinging problems. I religiously ran Sunoco 94 Ultra.
I am still having trouble finding pistons, which is what motivated this post. I guess I knew going into it that FE parts are still scarce, but theres still less available that I had thought. Diamond quoted me $685.00 (41002's), Probe said 800-900, Egge machine said 300.00 for KB's, and Summit tried to talk me into 9.5:1 TRW's for 295.00...but nothing seems to work out CR wise.
I am still looking, but based on your advice and info, I would'nt be afraid to consider something 10.5:1 or so. Theres also more variables than I had realized which makes this thread even more interesting.
Greg