Jim asked me yesterday on Chat about my brakes, so I figured if I'm compiling info, I might as well share with anyone interested 
All prices and part-#s listed are current as of today, 01-25-06
Modifying stock DRUM spindles to use stock 11 DISC BRAKES on 67-69 F-body (Camaro, Firebird), 68-74 X-body (Nova, Omega, Ventura, Appollo), and 64-72 A-body (Malibu/Chevelle, Monte Carlo, El Camino, Sprint, Skylark/GS, Cutlass/442, LeMans/GTO)
Spindles: $0 (assuming your car has drum brakes on it.) These can be converted to disc brake spindles with an angle grinder in about 20 minutes each.
Caliper Brackets .................................................. ............$79.95 pr +shipping
Bolts .................................................. ..........................$1.95ea (x2) = $2.90 pr
Backing Plates (optional - you don't really need these)............................$39.95 pr
*note: I used Ground-Ups prices because their website is easiest to navigate. Other sources may be cheaper, or have cheaper shipping*
The procedure for making disc spindles from drum spindles is simple. Bolt the caliper bracket tight. (but loose enough so you can rotate the bracket) to the lower bolt boss on the spindle. Then start grinding on the upper bolt boss on the spindle until the bracket can sit flat on both the upper, and lower surfaces. You will need to remove about 5/16-3/8 from the upper boss (estimated - I never actually measured).
The rest of the parts can be bought at any parts-store
NAPA part numbers and prices: (retail price)
Calipers w/ hardware #542-2016
17.75 ea + $9.00 core = $53.50 pr
- they include the caliper bolts and copper washers for the brake line.
Premium Brake pad set #AE728A
.
.........
.
.. $30.47 pr
Economy Loaded Calipers
..
$28.70 ea + $9.00 core = $75.40 pr
Premium Rotors #85532
..
.$77.31 ea (x2) = $154.62 pr
Economy Rotors #4885532
.....
. $46.88 ea (x2) =$93.76 pr
Inner bearings #BR6
. $7.31 ea (x2) = $14.62 pr
Outer bearing #BR2
$7.45 ea (x2) = $14.90 pr
Seal #17187
.
..
$2.08 ea (x2) = $4.16 pr
69 camaro brake hose #36672
....
$18.92 ea (x2) = $37.84 pr
on chevelles, drum cars had a different bracket, and the camaro hose fits better.
Banjo bolt #82701
.
$3.46 ea (x2) = $6.92 pr
Total: (Economy)
.......
.$330.45
Total: (Premium)................
..$ 439.83
REAR Disc Brakes for GM 10-bolt &12-bolt
Brackets from Steeltech Solutions: .....................$89/pr +$10 shipping = $99
Again, the rest can be bought at any Parts Store (Prices & Part #s are from NAPA):
Rotors Rear 11 rotors for 80 Trans-Am #85774... $41.16 ea (x2) = $82.32 pr
Loaded Calipers (w/ E-brake)
...
. $127.46 ea + $66 core = $386.92 pr
85 Caddy Seville rear disc calipers.
Loaded Calipers (w/o E-brake)
.....$34.75 ea + $22 core = $113.50 pr
85 Camaro FRONT calipers. (I think I bought mine for ½ that price from Auto Zone)
Hoses for 85 Camaro front
.$13.79 (x2) = $27.58 pr
Sub-Total w/o E-brake
...
.
. $322.40
Sub-Total w/ E-brake: $595.82 -cheaper just to buy the kit from Steeltech: $499.00
Then to make everything work properly, I used:
68 Corvette manual Master Cylinder (NAPA #101371)
.
............$20.69
Power Brake booster 69 Chevelle (NAPA #5471105)
.....$81.87
Wilwood adjustable proportioning valve (Summit Racing)
.......$50.00
Sub-Total:..................
$152.56
My Sub-Total because I used a $25 used booster from a junk-yard:..
$95.69
TOTAL (With all NEW parts, but done as cheap as possible)
.
..$805.41
(upgraded parts prices listed so you can calculate your costs accordingly)