10.95" Front Disc Brake Kit (Stage 1)
Mopar 11.75" Front Disc Brake Kit (Stage 2)
Everything in the above kits is new, with the possible exception of the caliper castings. They are based on OEM parts. The second kit listed may not clear 14" wheels.
You can look for the spindles and caliper adapters in the used market, but they aren't plentiful and are often expensive. Everything else is available through normal parts sources. Even though they may not be stocked locally anymore, most can be had next day at the latest. All service parts can be had through online sellers pretty quickly.