That "raised rear hood" situation was quite popular to deal with high-speed overheating on Mustangs and such. Might be that they had such stuffed engine compartments and marginal cooling systems to start with?
Cars are NOT universal, especially back then. What worked on one brand might not work on another brand, especially NOT in the same corporate parentage, by observation.
First thing, get a 180 degree thermostat in that motor with some coolant in it. At least, that keeps things from rusting!
Second thing is that, by observation, when those cars were "used cars", they NEVER had an overheat problem in the TX summers as long as the cooling systems were in good condition. Our associates in AZ might have needed something extra, but not in 95 degree F TX summers, with the a/c running.
Third thing is that if you have a 26" radiator, you need a "332" radiator, which is 3-core, from whomever. If you have a 22" radiator, if you do not have a fan shroud and clutch fan, head in that direction. Whatever you might find in Summit or similar will NOT be a direct-fit situation, which means you will need to fabricate something to hold it to the core support. More "black cloud"?
I used to put new Modine radiators in everything if I needed something like that. I could buy a new Modine for just a bit more than a radiator shop re-do, plus get OEM-level parts and OEM-level solder, which I knew would last at least 3yrs with good coolant maintenance. Since Modine is not around, Spectra seems to be the new "high quality brand" item (and costs like it too).
Check for a large radiator shop which does repairs for big trucks and such, plus sells new radiators to dealership and private body shops. You might find the best products and prices there. I understand and relate to the "prestige" of dealing with Summit or Jegs, or getting an aftermarket aluminum radiator, but you need something that will bolt right in rather than having to fabricate something to make that aftermarket item fit what you have, by observation.
I understand your wanting to give credibility to your friend and his Ford Iron, nothing wrong with that, but that's for "Ford Stuff", not Mopar-related stuff. In the car hobby, one of the toughest (and possibly most costliest) deals is learning "who to listen to", even within the Mopar ranks, by observation. This is part of the learning curve in dealing with vintage vehicles.
A key thing is that, especially back then, you don't fix a Mopar the same way you fix a Ford or GM vehicle with the same problem. Each OEM had their own unique engineering approaches and those need to be respected, generally. Sure, there can be some overlap, but other things just get "cross-threaded" if you try something different.
As to the coolant temps you quote, nothing the matter there, either way. When our '66 Newport 383 2bbl w/factory a/c was newer and growing older, it never got hot enough to turn on the "HOT" light (Plymouth's and Dodges got gauges), with the factory spec 180 degree F thermostat. The engine never smelled "too hot" or acted that way, either. On my '70 Monaco 383 4bbl with factory a/c, if the heat gauge got past 3/4 scale, something needed attention, as it usually ran at or below the center mark.
Is the flap on the bottom-side of the hood still there, which helps route incoming air through the radiator rather than over it?
Some thoughts and observations,
CBODY67