67 chevelle pad recomendation

[Wagonman1967]

Hi Folks, This is my first post on this awesome site. Some info on the car,1967 chevelle wagon, small block 5spd tremec. I converted from 4whl drum non power to the 68-72 disc setup non power. Still has rear drums. 7/8 bore master, 10 lb valve in rear ckt with an adjustable prop valve. I am looking for some better performance out of this setup and figured the pads would be the easy- cheapest way to start without going to a power booster. I have been reading lots of posts and searches. I originally had a master from a 70 Camaro non power disc/drum app that was 1in bore. When I did the trans upgrade I also added the 2 valves in the rear ckt. well lets just say the braking is less than stellar. Pad swap first? Any recomandations on NAPPA part # organic, semi metallic, ceramic?? Thanks... Just threw NAPPA in as it is the only thing out here in the Oregon sticks.