I think I'll try a new radiator first. Need to stick with one that the fan shroud will fit on it so will probably get a 3 row 'stock style'.
I've played with the mixture, thinking it was running too lean and getting hot. I used to have the timing too advanced so I backed it off but no change. I ran an oil cooler for awhile but that didn't make any difference, except it kept leaking oil.
My prior Z didn't have these issues and I drove it when it was 100+ and this one didn't seem to initially but since it is so seasonal it is hard to remember exactly when it started. I also get vapor lock in this one and never had it in the prior one; and these are the same carbs I was running on it but that is another thread.
I have heard that the heat from radiator repairs can shrink the tube openings through it so maybe the leak repair caused some restriction.
The last time I checked the compression it was okay but I've also wondered if I'm getting a lot of blowby at higher rpms that is heating the engine up.