heating up a little more

Ignition timing at cruising speed is a really big deal.
At 2800 rpm my lil 11:1/367 likes over 60degrees. At 65=2240 in overdrive, (manual trans) she still likes ~56 degrees.
My hooked to the sparkport Vcan, is set up with 22 degrees in it, which it adds to whatever the D is doing, whenever the vacuum is enough to pull it in, beginning at about 1600 rpm.

You may know the following; but I think it bears repeating.
The optimum point for the completion of burning and transfer of energy to the crank, of the expanding gasses in the chamber, occurs at about 25 to 28 degrees AFTER TDC, irrespective of load or rpm. It is the job of the distributor, at the prompting of the tuner, to make that happen.
If the crank at WOT receives maximum pressure too soon, the usual result is a loss of power, and detonation.
If the crank at WOT receives the pressure too late, the result is a loss of power, and overheating, as the expanding gasses chase the piston down and send the heat into the coolant via the rapidly growing surface area of the cylinder walls. The still burning gasses are then mostly pumped/ partially pulled out of the chamber, heating up the ports on their way out.
This last scenario only gets worse at Part Throttle and Cruising.

You can figure out your optimum cruise timing pretty easy; here's how I do it;
First you gotta know your cruise rpm. Lets say it's 2400, just for easy of explaining. And second, you must have an operational Vacuum Advance System.
So, in Neutral, rev it up to ~2200, and set the throttle on the nearest fast-idle step. Then just grab the D and advance the timing until the rpm no longer increases. Next, set the idle speed to 2400, and again zero in on the fastest rpm by increasing the timing. Then, with the engine at cruise rpm, read the timing, and subtract three degrees for load, and write the number down. Finally, put the timing back to where you started and return the engine to idle.
What you have just done is find the magic ADVANCE (BTDC) point to achieve the 25 to 28 degrees AFTER TDC max pressure point, at 2400rpm with no load; and with 3 degrees subtracted for safety, which you can hunt down later.
You can find the same point for any no-load cruising rpm you want to hone in on. And you can make a graph, connecting the data points together; thus giving you a target line to aim for.
You can mod your factory Vcan out to about 22/24 degrees, by cutting off a portion of the stops, on the arm.
The degree of difficulty to achieve this cruise timing will be directly related to the shape of your PowerTiming Curve.

With a non-programmable timing system, some sacrifices will be required. I solved some of those with a dash-mounted, dial-back, ignition retard box. Mine is adjusted to give 6* retard and 9* advance.
I use the retard to slow my idle to drive more slowly in first gear.(manual trans)
I use the advance at hiway speed, to zero in on the optimum cruise timing. And
I use 2 or 3 degrees, to flesh out the power-timing from time to time, which is set to just ~32* at 3200 rpm. (alloy heads @11/1 Scr/278psi minimum cranking pressure).
Just trying to help.

Btw
My cooling system, running the same parts that you have but with an ancient 26" A/C rad out of a 1973 Dart 318, ( yes coming 48 years old ) runs a solid 205 to 207 degrees (by IR gun) irrespective of the ambient temp, or how badly it is being abused, with a rated 195* Milodon Hi-flo stat.
I realize my engine is just a 367, but by it's trapspeed of 93 in the Eighth, it is pretty peppy.
Oh, yeah, fresh cold air from somewhere/anywhere is your friend. I cut a hole in my hood, aimed it straight down into the airhorn, and sealed the underside of the hood to it. Much like you did.