That one is on the front end of the passenger's side lifter oil gallery. It will read several pounds lower than the port beside the distributor housing. Be aware that on some later model 327 engines, that the port above the timing cover DOES NOT have a passage drilled all the way to the lifter gallery- - - -it's just a dead end hole threaded for a 1/8" NPT pipe plug. You will get very low, or no oil pressure on a gauge connected to that port. It was originally used for 1955 only 265 engines that used a bypass oil filter. 56 and later engines had a full flow filter provision cast into the block back by the driver's side bell housing area.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!