I converted the Pink MG (a.k.a. Angelica) to front disc brakes about a year before I did the rear. I did not have the lock-up problem due to the fact that I had already “softened” the front suspension by removing torsion leaves from the beam tubes. You are correct in the fact that the light nose weight and too much front “spring” is what is causing the lock-up. No weight transfer under braking is the biggest culprit.
I converted the rear to disc for another reason. I had a bad axle bearing in the right rear. I figured to go to all the trouble of replacing it, I might as well convert to disc. I bought an EMPI kit (w/parking brake) from http://www.peekperformance.com . The hardest part was bending new hard lines.
The front disc’s were standard on ’68 and up Kharmann-Ghia models. The front conversion kits are nothing more than these parts. It’s also important to know that the “wide-five” bolt pattern (king pin/swing axle) kits are much more expensive than the “4 bolt IRS” kits. I’ve had a few inquiries on my posted classified for VW parts and advised future builders to use a ’68 up IRS pan for their build.
The ’68 up Beetle/Kharmann-Ghia master cylinder is the same for the disc or drum. VW Trends ran an article on how to modify a later model VW bus master cylinder for use with these conversion kits. The 4 wheel disc conversion alone is a 100% better than drum, but this master cylinder mod elimates the “squishy” VW pedal feel and makes the braking even better. I’ll try to find the magazine date and post the article.
Incidentally, I’m sure we all know that VW Trends and Hot VW’s magazines are great sources for VW tech articles and vendor sources.