Disc brakes from my parts car

The 4 piston caliper K-H disc setup on my '71 340 Duster works great and you will get very good performance from the setup.

New rotors or just check the runout on the setup you have for possible cutting the rotor pair you already have, rebuild the calipers (there are caliper rebuild kits available --- new seals,etc. --- scuff the pistons when you dis-assemble and look for bad pitting --- if piston pitting is bad --- look at your options --- rebuilding your current calipers is not that expensive).

Make certain you get the metering block off the disc brake car, as well as the proportioning valve.

Moving to the 4.5" LBC makes sense if you have a drum setup and you do NOT already have the SBC disc setup.

In your case, and in my case, we already have the SBC discs, so stick with it!

People who move to the 4.5" LBC setup spend a lot of money on the conversion, when they add in the cost of 4.5" LBC wheels, 4.5" LBC rear axles, 4.5" LBC drums on the rear (some guys just re-drill the rear drums from 4" to 4.5" but that is not the best way to go).

Centric rotors are available in two grades: a basic $39.99 version and a premium version with better materials and better vented cooling for ~$90.
Raybestos and Wagner rotors were in the upper $60 range - Dec.2007.
Summit has drilled/slotted SBC rotors for $79 if you want bling (not me)!

Disc brake pads and hardware are also available; high perf.pads are available from Firm Feel if you are looking for a really great setup.

Good luck with the swap, and take a look at the old threads on this forum for more source info. on parts sources...