Hey dude.
My thoughts:
The oil pressure sender need to be plugged in the engine case.
Most common place is where the sending unit for the light is placed. You can put a T-piece between the sender and the case where you can put the pressure sender between.
The oil Temp sending unit also can be srewed in the case but need a hole tapperd....
A second solution is a sending unit that replace the dipp stick.
Oh .... DO NOT CUT A HOLE IN YOUR DASH....There are enough places where you can get rid of those meters... like the twin glove boxes, Or remove that wind-up clock in your radio...
Greetings.
ZELENSIS, coachbuilt body from the 50's on a vw platform made in Belgium. Peter the heb detective