Some Info on the disk brake conversion for those looking to update to disk brakes on the front of the AH 3000:
My car came from the factory with Girling type 14 disk brakes on the front. These were upgraded by Austin Healey when they rolled out the 1964 (BJ8) 3000. These later cars came with Girling Type 16 calipers and slightly thicker rotors. The same rotors and calipers were used on other British Leyland vehicles.
The brake mounts on the early disc (and I believe drum as well) cars like mine had caliper mounts that were bolted onto the hub, and they had 3.25 inch spacing for the caliper mounting bolts. In the later cars the hub had built in caliper mounts that were 3.5 inch apart. Many after market calipers have 3.5 inch mounting holes.
There are two suppliers in England (Cape International at www.cape-international.com; and Denis Welch Motorsport at www.bighealey.co.uk) that sell reproductions of the front caliper mounting brackets from the early front disc cars (thru BJ7). They're fairly pricey though, at �117 for the pair w/bolts. They can be a source if you need these for this upgrade.
Both of these companies also offer the calipers that bolt onto the 3.25 inch mounting holes on these brackets, but these calipers are available here in the US for a lot cheaper.
With these brackets (which came stock on my car) you can mount the early model rotors and calipers (Girling model 14) to make your front drum car have the stock setup of the early disk brake cars.
Problem: the early model rotors, pads and calipers are not easy to find and there are few options for improved pad linings or slotted discs and such. When you do find them, they're more expensive than the BJ8 model brake parts (aka Girling model 16), and they're not as effective at stoping the car.
Solution: mount the later model (BJ8) discs (which are of the same diameter as the early discs, but thicker) and install the calipers from an early 70s (I got calipers for a 1974 from Kragen for $37 each) Mercury/Ford Capri (aka Girling model 16 Metric). These calipers have the uncommon 3.25 inch bolt spacing yet allow for use of the bigger pads and thicker rotors.
I purchased semi-metalic pads for the BJ8 ($19 from Victoria British) and they fit the Capri calipers perfectly. Also got the slotted rotors from Moss Motors for the BJ8/MGC and they fit perfectly as well.
The only problem I had was that these calipers use a metric 10mmX1 flare nut and not the 3/8 inch X 24 flare nuts that are everywhere else on this car. They look damn close, but they won't interchange. I used a prebuilt 20 inch metric straight brake line (metric fittings on 3/16 tube) from Carquest that I cut in half. On the cut ends, I installed the original SAE female 3/8 inch nuts from the old calipers and double flared the ends. Instant adapter pipe with SAE on one side and metric on the caliper side.
For the rear in my car I changed out the Ford drums (it's got a Ford 8 inch rear axle) for Cadillac Eldorado calipers/with Lincoln Mk VII rotors.
For the master cylinder, I installed a 1 inch Wilwood combination remote tandem master cylinder that gave me dual circuit with remote reservoirs. I have under hood heat issues and this allowed me to put the reservoirs further away from the exhaust manifold. This master cylinder also bolts onto the Healey's pedal box with no modification and allows for continued use of a hydraulic clutch if needed.
With a Wilwood proportioning valve for balance, it stops a whole lot better than it did with the original setup with marginally lighter pedal effort.
I've never driven a Big Healey with a brake booster, so I don't know what it feels like, but I'm planning on adding a remote booster of some sort later on due to the very heavy pedal (compared to modern cars).