There are factory power brake boosters available on eBay and on the "Truck Parts For Sale" forum. I have personally done the power brake conversion on several '64-'66 Chevy trucks, utilizing the factory power brake booster. The process is relatively easy and requires very few tools and little know-how.
If you are using a factory power brake booster, correct for the '60-'66 Chevy trucks, you will need the factory power brake booster, mounting wedge, check valve, vacuum hose, hose fitting to boss in intake manifold, mounting fasteners and push rod. The aluminum mounting wedge, that mounts the booster to the firewall, ensures the push rod through the firewall to the pedal has the correct geometry.
If using a factory power brake booster, you can use your factory single chamber master cylinder, simply by removing it from the firewall and keeping the brake line connected. It will then attach directly to the face of the booster after it is attached to the firewall. If you are interested in this application, I can give you a play-by-play of the installation procedure. Attached is a photo of a factory power brake booster installed.
Factory power brake booster
