May be irrelevant, but my sister has a 1976 Dodge 22ft mini MH with a 440 and 727 trans. She bought it from a friend of mine who owned it for 15 yrs. and used it to pull a 28ft enclosed trailer with a 3,000 lb race car.
It also has an overheating problem, if it's driven over 55mph it goes up to 215/220* if driven at 55 MPH it runs 180*. I talked to my friend who owned it, he said he never worried about it, it alway ran those temps. It scared my sister and she had the radiator rebuilt, flushed the block, put a new waterpump and clutch fan on it and notheing has cured the problem. It does have engine AC and a trans cooler mounted in front of the radiator.
It's now for sale for $2500.00 because she doesn't use it anymore.
Zip.