Small Engines (Lawn Mowers, etc.): B&S oil pressure, oil pressure gauge, shaft model

Question
I have a B&S engine. I want to hook-up a oil pressure gauge. The engine is a 18 hp verticle shaft,
model 422707
type 1225-01
code 90011512
There is no oil filter on this model.I was told that I could install the gauge hose at the auxilary drain plug. which I did, but there was  no oil pressure reading. So I'm thinking about changing from a mechanicle gauge to an electrical gauge using a sending unit in the drain plug.
B&S uses a low pressure switch #491657S in the auxilary drain plug which activates a warning light when the pressure drops to an unsafe level.
MY QUESTIONS are
1. would an electrical gauge and sending unit installed at the drain plug produce a pressure reading?
2.does this engine produce readable oil pressure?
I Thank You for any information on this problem.
Curt  

Answer
If you had the correct sending unit, electric, you could get a reading but I'm not sure which sending unit would work.

The engine does not produce much pressure so I doubt you would get much of a reading on a mechanical oil pressure unit.

I'll have to check to see if Briggs even publishes an oil pressure spec for that engine.

Eric