What is the stock CR on a 71 350(275)hp?

Probably about 9.0:1

Probably about 9:1 or 8.5:1. They have big chambers (75cc) and flat pistons. Possibly even 8:1 even? Mine's a dog and I feel could run on like 82 octane if they had that.

'71, 270hp/350 is 8.5 to 1 CR..

And more than likely down around 8.+ to 1 is more like it if the motor is stock/average and not had any sort of blue-printing/tweeking done to it??

pdq67