I run my 10.65:1, aluminum headed, L82 cam, 383 on 87, 89 or 91. It doesn't ping on 87, even in summer.
My LM1 after being rebuilt pinged a whole lot more than my 383 and that has pretty low compression(8.5:1) but I'm running that XE262 cam. I can't remember how far the pistons were in the hole, but it was a ways so my quench is way over .040.
The quench on the 383 is pretty tight, like .032-.035. The guy who built my engine said that the tight quench, L82 cam and aluminum heads would allow me to run 87. I didn't believe him, so I ran 91 but eventually I tried 87 and it works fine.