[Old Crow]

For an SBC, I'd just use O'Reilly's or whatever auto parts store is close for the pump. Pulleys can come off Ebay(remember you'll need a double groove w/p pulley, a double groove p/s pulley and 3 grooves on the crankshaft pulley).
A/C, I'm with Solidaxle(but then, I'm a VA dealer)on the Vintage Air
Radiators I've been buying from Champion. They're on Ebay, but they also have their own web site, too.
Vintage Air has an optional trinary switch for electric fans. You'll also need a temp sensor/switch to go in the engine. This way the fan will come on either when the engine temp reaches a desired level, or when the a/c clutch engages.