Mercruiser 502 - Electric fuel pump oil pressure switch / sending unit?

[Slide]

I just installed a new electric fuel pump in my carbureted 502, deleting the mechanical system. I need to add an oil pressure switch so the pump doesn't run with the key on and engine off. Right now the sending unit for my oil pressure gage is occupying the spot for the switch. Is there a unit that will both switch my fuel pump and send a signal for my gauge? Or is there another location I can install the switch?

Also, which switch should I order? The block is a 1995. There seem to be a few options.

 

[Bt Doctur]

one that has a normally open NO and a normally closed NC , basically a 3 prong pressure switch available in most good auto stores. Two areas to tap for pressure are the port just behind and to the right of the dist. most times the oil pressure sender is mounted there. so just add a T fitting.
the other place is just above the oil filter ,sometimes occupied by the "no oil pressure alarm switch", can T in there also.
I would use a cube relay, so you don't burn the contacts in the pressure switch. some E pumps draw a little more amps than the switch can carry