On my 1985 Barth the oil pressure gage just goes from 0 to 60 with 3 increments in between. When I am idling is rests about in the center or at 30. When I step on the gas it goes up to 45 or 50. Is this how it should work?

This may take some effort but compared to a lost engine it is the best solution. Have a mechanical pressure gauge installed temporarly as a test gauge to verify the coach's electrical gauge readings. If they are off significantlly replace your gauge and sending unit. We use Stewart Warner deluxe or Murphy switch gauges.
Ted Sierocinski

pressure increases with rpm is normal