After verifying gauge readings as rumblefish360 suggested, I would start wondering about that fan clutch setup. I had several different replacement fan clutches that are way too tight and never loosen up. Fuel mileage went to **** from the extra drag, and they were very noisy from pulling so much air. You may not hear the extra noise on this beast.
I am no expert, but maybe something to consider.
Also, does your EFI use a different coolant temp sensor than your gauge? If so, do they match or agree with similar readings?
At least it’s not running hot. That’s good.