Hmmm.

Using the stock ifs calipers on straight axle rotors would explain why you keep losing caliper seals. They are made for the thicker, vented disks. Upgrading to V6 calipers (bigger pistons, more fluid capacity), Land Cruiser rotors from 81-83 Toyota FJ40 or FJ60, Sky Mfg. spacers if you have IFS hubs or simple wheel spacers if you don't, and FZJ80 or some years' Taco/4Runner master cylinder (1" bore, moves more fluid/stroke), and a V6 or t100 vacuum booster will help. Erik Bibelheimer has quite a discussion on brakes and options, I forget the link but a search should reveal it.