If  you had stated that you had bought a pulley to speed up the pump because others here have wrote about it but it didn’t work and why I would have started with the next paragraph.

I’d make a 1” wide wooden wedge that copied your 1/2” belt pulley and start around the 3/8” pulley making it wider with a hammer hitting the wedge. Do it vertically with the pulley on a 2x4. Take your time moving the wedge 1/2” at a time and go around the new pulley 3 or 4 times. You’re only reforming it 1/16” on each side. Bolt it on the hub after the checking the belt in the groove and make sure it’s straight. Hot Rodding at its finest. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

It  would have been great if you could have increased the speed of the pump and fan, a double win.  You can observe the flow by fully warming up the engine with the radiator cap off and then observe the flow of coolant. An assistant can put the vehicle in gear with brakes applied while you check the flow in the radiator. Some have reported no flow under these conditions. This will at least give you an idea wether the electric fan will help or not. If you have a manual transmission, picking up the idle may help also.  You have a good understanding of the 6 volt/generator electrical system's limitations. Good luck - let us know how it goes. 

64F100 57FAIRLANE500

It would be a lot easier if I could find a pulley for a 1/2 wide belt, the parts guys of today are programmed to the computer. I have also thought about going to a machine shop and see what they say about enlarging the pulleys width. Oh well nothing happens fast with this car, every item Ive repaired or replaced took time to get done. Thanks for you guys input I really do appreciate it.

I know this is not the way to do thigs but have you explored how your 1/2" belt rides in the 3/8" shiv pulley?  Maybe the manufacturing tolerances are such that it might work. Sometimes off-shore tolerances are pretty sloppy. 

64F100 57FAIRLANE500

Ford Dearborn,  I would have suggested that too. All he needs to do is change the pulley, align it properly with the shim kit, and use the 1/2" belt in the 3/8" pulley. I would adjust it once a month and in 6 months or so the pressure will probably open the pulley wider. I didn't because if it was too tight it might cause a bearing problem with either the generator or water pump.
Before the wooden wedge way I would have done it with a pair of lineman pliers or a channel locks bending the sides out a little bit. I'm sure I did when I was 16 and never gave it another thought. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

You guys have gave me some ideas that I hadnt thought of.If I was 16 I would do the plier method and if parts and pieces werent so hard to find I would put a 3/8 belt on it and see what happened, right now Ive got the front fender off and I should have the new on this week " it only took 2 years to find a fender that I could afford and was close enough to go get" and I hope to have everything put togther in the next week or so. It will be a few weeks before i get back on the temp issue and if you guys have anymore ideas I would apprecaiate your thoughts. Oh yeah if you need any parts for a fairlane I found a guy in Tenn. that has a LOT. His name is Norbert Doll.