Agree, 9.5 leaves a margin for error.
Had #13 heads on a o-decked 400 at 10.0 with a 744HL cam.
Used 93 for 2 yrs(about 5000 miles).
Sold it to build a more powerfull engine. He wanted to see the crank-n-cam lobes after hear'n it run.
They still looked new.
That tells ya what good machine work, assembly, and tune can do.
Should of never sold that engine...