Man, I have never had a problem with fuel boiling, even in 100+ degree days here in Sacramento. I don't have an electric fan (won't fit). Just a small phenolic spacer and an electric fuel pump. The heater plate is bypassed as I don't drive the car when it's that cold - however if I did and I wanted that heater I would just move my heater control valve closer to the water pump and let it divert the heater plate too.
I'm not so sure you're going to get the result you want from those aux pumps. The small Bosch ones you're talking about are not used for cooling the engine, they're used to assist the heater core or, as in the case of my XJR, to help cool the intercooler due to a fundamentally dumb plumbing design.
Those pumps have small 5/8" (IIRC) I/O and don't move much coolant. It would take a long time for one of those things to circulate a "load" of coolant through the radiator. I think you would *need* an electric fan running to have any meaningful effect.
IMLE, the weak component here is not fuel temperatures but ignition strength. On hot days with the coil bolted to the side of the motor the ignition system gets weak and has a really hard time getting the car started. When I first got the '62 hot restarts were a perpetual concern - I used to plan my commute home to ensure I didn't need to stop for gas and have to end up sitting around waiting for things to cool down.
Relocating the coil to the shock tower and installing a Pertronix with direct-battery power fixed that up handily.
Admittedly I've not had this situation, but if a fan on the carb isn't curing your hot restart issue, I don't think your issue is the fuel. And, I don't think those little Bosch pumps will have a meaningful cooling effect anyway. Personally, I would look elsewhere.