Did I miss it, or have you still not posted the Anti-freeze to water mixture? As mentioned, too much anti-freeze will make it run hotter..... If your anti-freeze is more than a 50/50 mix, it may very well be part of the problem.

While I realize you don't have a clutch fan now.... adding the MP clutch fan setup may very well help you out. I've had great success in the past using 440 A/C clutch fan setups on non a/c vehicles. They move LOTS more air and work great. That along with a good fan shroud has fixed any BB overheating problems due to air movement. Now if you're running WAY lean at idle....that could be another issue.

Where is your vacuum advance hooked to? Ported or manifold vacuum?