ElJaro,
Going to a higher viscosity
oil might actually give you
lower oil pressure as measured after the filter. There will be slightly higher pressure out of the pump - but more pressure drop across the filter.
*Toss the Fram filter! Do a search on this site for "
oil filter".
With the oil cooler and thermostat, 15W-40 is probably a better oil choice.
It
does sound like your clearances are a bit loose and you could stand a slightly stiffer bypass spring in the oil pump, but things are not too far off. I would drive it for a while and see whether the pressure remains constant. Put some miles on and check the rod bearings for wear.