oil pressure

I'm embarassed to ask this, but where does the oil pressure guage hook up?  
during the rebuild the machine shop dutifully filled, sealed or screwed bolts 
into all the open holes on my motor to keep it spiffy  and I can't 
remember/find it.  I believe it came out (1500 midget) forward of the starter 
and below 
the distributor, but even if that's the case there are at least three potential 
spots in that area.  Any specifics?

Thanks,

Mark M.