Here's a site for reference as to what colors go where:
http://www.oldchevytrucks.com/cgi-bin/htmlos.cgi/00929.3.2912304961818505530 Everything is body color, underside and all, with these exceptions: 1. Bumpers, inner grill bars, hubcaps -- light gray. 2. INNER fenders, running boards, firewall to fender braces, wheels, bedwood, bedstrips, mirror(s), spare tire carrier and supports, frame, axles, springs, differential, etc., radiator and mounting frame, that big piece the hand crank goes through -- black. 3. Interior -- see above site for correct colors. 4. Pinstripe around cab -- contrasting, depends on body color. See above site.
Or, just paint it whatever you want.