I was wondering if anyone may have a inexpensive up grade/fix for my '71 FJ40 the stock brake master cylinder doesn't seem to have enough volume or pressure for 4 wheel disc brakes? I tried replacement didn't seem to help

The 1/75-9/75 Master Cylinder is a 1" bore, and moves more fluid. A friend runs this setup using L/C front discs and the GM small caliper rear disc conversion(Monte Carlo Calipers?) and does not need a proportioning valve, but his truck is often loaded down a bit... Check around, there are other 1" bore M/C's avail.
HTH

I had the same problem, took everything off snd went to a GM booster, same dia. as the LC one snd s master cyl that went with it, they came off a early '80 s Cadillac. and I can lock up all 4 super swampers.....I have a pic if you want.