Are you sure the pinking is not caused by ignition problems rather than the compression ratio. It could well be that tired springs on the distributor counterweights are causing the ignition timing to go to full advance at lower revs than it should. Try the electronic ignition system before thinking about reducing compression. If the engine is running at full advance at too low revs that could cause overheating too. if you are having fuel vaporisation problems you could insulate the fuel lines by covering them with a neoprene tube.
I would suggest getting the unleaded conversion, fitting electronic ignition and having the car properly tuned. I suspect it will then run much better and cooler and a good deal of the pinking problem will disappear. Naturally a decent fan will always help in hot weather.

Peter

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