WTB heavy duty drums or disk conversion?

[Exille]

In the process of completely rebuilding my 69 GMC 1500, and the original manual 4w drums arent going to provide adequate stopping power by any means, im looking for some kind of heavy duty drum replacments or disk brake conversion for my truck hopefully in the $600 and under category, does anyone know where i could get my hands on something like this? im located about 35 miles southeastish of Sacramento if that helps...