The oil pressure sender is in the rear of the engine behind the intake manifold on our 88 460 in an F350.
There is also a pluged hole above where the fuel pump would be on a carbed engine. Looks to me like the PS pump would have to be removed to access.
I expect either one could be used for oil pressure testing.
Bad news is that neither can be easily accesed when the engine is in the truck.
The easy way would be to put a T in the oil cooler line if you have the external air cooler.