Geez, and I was getting a little concerned over my LB7 dropping down to 30 psi at a hot idle on a 100 degree day with 5W40 ROTELLA with a 600 idle(680 idle will hold right at 40 even hot idle). I guess my LB7 must be a fluke off as it holds some pretty high oil pressure no matter what oil I run or how hot out it is. Cold she slams right up to 70 at idle and drops down to 35 at idle when hot at 600 RPM's. After 1000 though she tends to hold 45-50, and even on a 100 degree day towing she will still go up to 65 or so when I get on it even with the 5W40 oil. 15W40 was even higher oil pressure, but she spins over MUCH better with 5W40.
Another thing to consider is changing brands of oil. I know when I build engines for customers(all gassers) I run 10W30 VALVOLINE for break-in then switch to 5W30 or 10W30 CASTROL GTX after a 500 mile break-in period. On every engine so far I have seen a noticeable increase in oil pressure going from the VALVOLINE to the CASTROL oil of the same viscosity. I know I used WAL-MART oil one time to flush out an engine in a JEEP that was ran as a submarine and it would only hold 5-7 PSI of pressure at idle, but when I dumped it out and went to the CASTROL it went right to 18-20 at idle. Also using STP oil treatment(the small blue bottle) will generally yield a 5-8 PSI increase in idle oil pressure on every engine I've used it in.