I've got an electric fan bolted on front of my radiator support for my a/c set up. It was easy to install and set up. The only difference between what you've got and what I've got is you would remove your mechanical fan but leave your belt/pulley in place to run the water pump.

Here's a link to an e-bay auction for a fan with a temp control module (vs sensor)that is an example of what you might use.

http://cgi.ebay.com/ebaymotors/16-H...iewItemQQcategoryZ34201QQitemZ4628668765

'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi