engine guru's ,need help

[Old Guy with 87 GT]

i posted all the specifics on windser power ......i know it's a technicle question ......but since i didn't get many replies(one) i posted here asking peaple to take a look at my post over there

it's been staying around 50-60 psi with hardly any fluctuation,.......it isn't the gauge(installed aftermarket ) it isn't the filter or oil(changed filter)..........up intill a week ago the pressure would fluctuate from 15 to 70 psi ......somthing changed and the pressure seems stuck around 50 psi .....whether it's cold or warm---at idle or 4500 rpm.....it fluctuates a little from 45 to 55,60 psi but not the way it alway's has since i've had the car.......the moters not running hot or making funnie noises ,so it's got me puzzled

i'm worry'd that it has some internal issues ,i have plans to rebuild moter when i get my tax return ,but i don't want to burn or score somthing driving it till then........i have to go to philadelphia next week (300 mile drive) so i'm worried as to what could cause this