20 hot idle and 40 hot throttle are 'safe' numbers.. but indicate a pretty well worn red tiger... well worn with LOTS of life left in it mind you.
I have some absolutely abused and used red tigers that run that sort of pressure.. and I expect them to keep doing that another decade or two before they get to be worrysome.
ideally, a good red tiger should start up cold and hit near 60 psi on cold oil with some throttle as the relief cracks in mid 50's... with hot idle pressures usually being over 40.
I used 15w40 C rated oil in 99% of my machines.
you may be lucky have have really thinned out oil. see what the oil change does for you.
standard cannister is a fram ch6pl or napa 1004 standard spin on is a fram ph8a, supertech st8a, motorfraft fl1a napa 1452 or 1515 etc... usually a 3$ spin on and 6$ cartridge..
post back if ya have any more questions.. 53-64 are my favorite ford years..