Whats everyone running for gears?

3.91s with suregrip. Only has 25" worn MT street slicks. Would like a taller rear tire for the 14" rear wheels. Just a play toy that was a track car but I want to tag it and be able to play on the local country roads. I live on what has to be burnout street. Long, straigt, isolated. More than a few of those marks are mine and it's easy to tell as I like to use the line lock so the rear end gets a little outta shape before I release it at redline.

Which brings up another question - what RPM should I worry about exceeding? No idea what is in the 71 cast date 340 except it has a steel crank. Revs like crazy!