My '68 B-body came with power drum brakes (Midland-Ross booster).

I did the front 11-3/4" A-body disc brake swap.

Finding a '67 and up Bendix disc brake booster is the next step if your looking to go the OEM route.

I found a Bendix disc brake booster from a 1967 C-body.

Booster Dewey is rebuilding it right now.

He's changing out the C-body input shaft to a b-body input shaft ($40).

As a side note, early C-body boosters used a different vacuum check valve, a twist-to-lock type, cogged hole in front cover.

Later b-body and Hemi-style boosters used a push-in type valve, round-hole in front cover.

Raybestos makes the Hemi style which can be had on Amazon for $11.

http://www.amazon.com/dp/B000C6ZPVG/ref=pe_175190_21431760_M3T1_SC_dp_1

The C-body valve I found NOS (picture attached).

Front Bendix booster covers are interchangeable and Mr Dewey offered me that option for +$50. I declined since I had the correct valve.

Aside from that, you just need to purchase a 4-bolt disc brake master cylinder and an adjustable proportioning valve for the rear brake bias adjustment.

There's more than one way to skin this cat, but in my case, I tried to keep it looking stock.

John