[T3] Overheating

[Know One]

I got my Sqbk back running again in the past month or so and have been driving it when I can. 

I took it on several drives and now I remember the symptoms it had when I stopped using it for my daily commute. 1967 dual port stock carb setup. 

When it gets hot, it ceases to idle and is difficult to restart. I have to pump and hold the pedal down to get it to restart, and I have to push on the gas to keep it running when at a stop.

Since I parked it a long time ago, I have resurrected it and performed the following:

Removed engine and cleaned up everything, so no nests or surprises in the cooling ducts and all intact.
Proper heads rebuilt and installed.
Gas tank cleaned out and all new lines.
All brake system components functional and filled with silicone fluid.
All the lights are working, FINALLY!
Lubed the front end.

Yeah, some of these shouldn't have any impact on cooling, but there they are.

I have the phenolic spacers on the carbs.
Stock air cleaner.

Any advice on how to approach the overheating problem?

Jeff '67 Sqbk