Whats a good tire pressure to run 28 or 32 or ??

I think you're comparing apples and oranges. The ZRX1200 has ~3 1/2" wide front rim and ~5 1/2" rear rim width, and runs on radial tires, ZZR600 is near the same. I don't see how you can compare those against the 1.85" front and 3" rear rims with bias ply tires.

.