What are you seeking to accomplish with this motor? Is it getting hot running down the road at 60mph or in traffic/stagin lanes?
First thing that struck me when I read the specs is that there are some mis-matched parts in that engine. Too much cam, a decent intake, with a decent carb, sitting on STOCK heads. Even if they have 2.08/1.74 valves, they are still stock ports.
A 3200rpm converter will build some extra heat, due to its looseness, but the factory Chrysler service manual gives the stall speed ranges for 1978 Chrysler V-8s, some of which stall that high with a stock/production converter in them. A 3.91 rear axle is good, but turning what size tires?
What width radiator? Obviously, the existing 4-core aluminum radiator is not working as well as it should, for some reason. Just because it is "4 core" and "aluminum" does not mean it will cool well due to the different fin densities which can exist. Lots or fewer.
Another reason could be the "high volume" water pump which is probably running coolant through the system too fast for it to evacuate (to the radiator) heat from the engine. Then what coolant gets to the radiator, at whatever velocity is rushed through the radiator before enough heat can be dissipated (by the cyclone-speed fans) before it gets back to the water pump.
The other thing I see is too much initial timing, although the total of 38 degrees BTDC total is good. Over-advanced timing can cause hotter running, no matter the thermostat's rated temperature. Have you had the car on a chassis dyno to check "road load" air/fuel ratio of about 14.0? Over-advanced timing can effectively lean the mixture, from what I learned years ago.
At night, when the fans deploy, do the headlights dim as they are pulling so much juice? At about 1500 engine rpms, when the alternator output starts to increase? Remember, if the fans are pulling that much juice, that is limiting the amount of voltage than can run the ignition system and electric fuel pump, which CAN affect engine performance. What alternator is on the motor AND have you done the ammeter bypass as chronicled in here by
@cbarge?
185 degree F thermostat? Chrysler used that temp OEM on B/RB engines in 1972, but all of the replacements were 180 degree F items. Is it a "Robert Shaw" style now sold by Mr. Gasket or a normal replacement part?
Lastly, 220 degrees F is NOT hot, considering that coolant boils with a 16psi radiator cap at about 260 degrees F, that atf starts to degrade at 290 degrees F, and motor oil (depending upon the brand) starts to degrade a good bit past that.
Is 220 hot compared to 180, sure it is. I, too, start to get a bit worried when the heat gauge needle gets past the center mark, but nothing is being hurt at that temperature. The related thing is that when you stop the engine at that temperature, a "heat soak" happens where the coolant can't move and absorbs all of the heat that is in the cyl block assy, which means that it can rise to closer to 260 degrees F as it sits there, even if the fans are cooling the radiator.
Although, to me, I see mis-matched parts, the things which can be done quick and easy are to put tine base timing down to 15 degrees BTDC, making sure the mechanical advance is completed by about 2000rpm and still hits the current 38 degrees figure. Then get the car on a chassis dyno and do a road load air/fuel ratio check to see where things are. Or with a quality air/fuel ratio function on a diagnostic machine, take the engine to about 2500rpm in "P" to do the check. Again, aim for 14.0 air/fuel ratio "at cruise". If you do have access to a chassis dyno, you can also load the engine to watch the AFR change with load until 5" Hg is reached under load (which checks for the power valve opening and its affect on the AFR).
That will be the cheapest and easiest things to check/adjust/verify without spending a lot of money changing parts.
Respectfully,
CBODY67
