66 Barracuda drum to disc conversion
It has a stock 7 ΒΌ, and preferably change to a 4.5 bolt pattern, since its more common with modern wheels
Then I'll assume you've got 9" drums. Dr. Diff offers conversion axles for your rear, with new 5x4.5 drums (if you want them):
Mopar Axle Pkg 7 1/4" A-Body 5X4 1/2" Bolt Pattern (pair)
So for power four wheel discs, 4.5" bolt circle, you're looking at:
Front disc conversion with ball joint adapters, hoses, 4Wdisc distribution block, 15/16 master cylinder
10.95" Front Disc Brake Kit (Stage 1) - $905.00
Rear disc conversion kit with new parking brake cables
Mopar 10.7" Rear Disc Brake Kit - $700.00
7 1/4 conversion axles with 3" studs for disc brakes
Mopar Axle Pkg 7 1/4" A-Body 5X4 1/2" Bolt Pattern (pair) - $298.00
Booster, brackets and linkage
Bendix Style Dual Diaphragm Booster for Mopars- $300.00
New front hard lines
Mopar Front Brake Line Selector for A/B/E Body - $85.00
Grand total for the basics: $2,288.00
The kit you are looking at is $1755.00 just for the front...
And to be honest, that $300 for the axles would go a long way towards a better 8 1/4 rear or an Explorer 8.8; which if you shop wisely would come with 3.5x/3.7x gears, limited slip and disc brakes, which in turn saves you the $700 for the rear disc kit...
8.8 swap