I'm one to try and support my local auto parts suppliers. Aside from supporting your local economy, if you have an issue with a part, you can just drive over there and get it taken care of. You can buy everything you need from your local auto parts supplier except for the dropped spindles springs, and the 6 lug rotors for the '73-'87 spindles. If you aren't looking for dropped suspension parts, I would just get some used OEM parts.
In case you're not familar with how easy it is to convert to front disc brakes, take a look at this thread.
http://67-72chevytrucks.com/vboard/s...d.php?t=367260
There are a couple more threads in the FAQ at the top of the main '60-'66 page.