Is this oil pressure ok?

The sending unit is installed next to the distributor, I have had it for a few years as well and at one point accidently had wires backwards on it, but it still managed to work which is weird. Also it's a marshall gauge? Are those any good? Debating on buying a mechanical stewart warner or auto meter
Dont know of Marshall gauges
I have had good performance with SW
I mentioned before your next step is to check the accuracy of your current set up.