Have a read of the 914 tech articles on the Pelican pages, that might help explain a few things.
This one in particular may answer some of your master cylinder questions
http://www.pelicanparts.com/techarti...rake_calc2.htm
I have 944 NA brakes front and rear on a 1302 and I find them okay on the street and once warm on the track I really like the way they feel and brake. They may not be perfect, but I suspect they offer better front to rear ratio than most people think. I use the 23.8mm side to the fronts as designed by Porsche. If you read the above tech article you'll see why it is done this way.
Friends with quicker cars than me would like to upgrade their 944 NA's (also on a 1302), but I really think it comes down to what you want and the use you give your car.
Out of curiousity have you compared the front to rear hydrallic ratio of this set up to early 911's, which are more tail heavy than our Beetles are.
Cheers
J