OK, please allow me to elaborate:

The radiator is NEW, so there isn't any crud in it. Besides, I flushed it right after I bought the car and it's super clean in there.

I have a 4-bladed fan at the moment, and there is hardly any noticable 'twist' to the blades. It looks to me like someone was searching for free horsepower and decided the fan was pushing too much air.

I just removed a good add-on temperature gauge and re-installed a stock one. The old gauge generally read OK except when I was pulling a long, steep grade. the revs go down and the speed goes down, and the temp goes up.

No, it hasn't actually boiled on me yet, although I found the overflow tank empty and had to add all my emergency drinking water to get it to the proper level. Looking at it today, I think I will have to add a little more water before I go anywhere very far from home.

The fan that's on it measures 11 inches, with plenty of space left over, so a 13 inch fan will do nicely. I may have to add a 1 inch spacer to clear the belt, but that's no big deal.

I've run good quality flex fans on road cars and race cars forever, so I should be able to find one that will stand up to the task without exploding and throwing shrapnel into the works.

The ones to avoid are the old ones that used fiberglass blades. Good stainless steel blades are usually a sign of quality.

One factor that may be causing the car to run hotter than I like is that it still has the radiator from the B-18...or it may even be from a B-16.

Regardless, it is pretty small, has only two rows of tubes, and there is no shroud to channel the air effectively.

If I get the money, I'll have a four-row radiator built and quit fretting about the engine temp. :-)