If the actual pressure at cruise speed is as low as that fancy gauge indicates, the engine is on the ragged edge of disaster. Badly worn connecting rod and main bearings cause low oil pressure at cruise speed. Either fix it now or wait until it becomes a boat anchor. You can ask John Milliman (the owner of the Stovebolt site) if my analysis of oil pressure symptoms is accurate. I took one ride in his truck with a newly-installed "good condition" used 261 engine and warned him not to drive it again until he pulled the oil pan and inspected the bearings. A couple of rod bearings were totally worn out, along with two cracked pistons.
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!