Reply to "temp sensor"

Well, I didn't want to hijack the thread, but here goes.
Yes, running a stock bore '66 block 427 sideoiler, solid lifter cam, dual 650 Holley's.
Duel electric pusher fans wired to run in key on position.
Tunnel port heads and intake.
Last summer the temperature would climb to 195*-200* in slow traffic, it would come down, but very slowly once moving again.
I changed out the T-stat to a 180*, all it had was a restrictor plate installed. P.O. used it mainly on the track from what I can gather.
That helped, but the ambient temps. had dropped by the time I swapped it out, so not a deff. fix of the issue.
On a 65* day, the engine temp would climb to about 185* befor the t-stat would open and drop the temp. down to about 170*. After about 30 min. of drive time the temp. would stabilize at around 180*.
I don't think the radiator cap(s) are the main culprit, just a contributor.
The cooling system was upgraded, but I'm guessing the upgrade was to 351C spec.s, not 427 cooling requirments.
It's possible I have a flow issue, either a worn or missing water pump impeller or a slipping belt.
I can get the temperature to drop by bringing up the rpm's, but only briefly before it starts to climb again.
I ran it yesterday, 80*-90* day, had to shut down twice and run my fans with the motor off to cool what was in the rad. and then bump the motor to pump the cooler fluid into the block.
It's climbing up to 210*, that's as hot as I'm willing to let it go without shutting down.
I need to pull the bulkhead and check the belts, I had planned to replace them last fall with the t-stat, but the "parts store didn't have a belt close enough to fit and the one on the car was in good shape. I also need to try and get a casting number off the water pump to make sure I get the right one ordered.
No strange noises, gurgles etc., after doing the t-stat I lifted the rear of the car to fill the cooling system. (heard lifting it helps keep air pockets out when filling?)
No coolant leaks, just had it on a lift doing the fuel pump and all the coolant lines looked good and no kinks to restrict flow.
I couldn't even see that there was any coolent seeping from the "weep holes" on the pump.

I think it's a flow issue more than anything, either because of a failing pump, or not enough flow designed into the 427 swap.
Which brings up a question. If it comes down to needing more flow, I have a 2nd thermostat housing access on the rear of the intake. Would it be possible to tap into the aft tank and run a coolant line to the rear of the intake?