Several things to consider.
1. How much room between the front of the engine to the radiator?
2. Do you already have brackets for the motor to mount accesories? if so for long or short pump.
3. Electric fan or belt driven?
I went with a long pump on my 39 but I set the motor back as far as I could. Only about 1/2 inch between distributor and firewall. I also had to run different valve covers than I was originally going too.
As far as a radiator I had mine built by PRC, it was about $500 but it is a great product. No cooling issues at all and Im running a mechanical fan with no shroud.
