Hard to tell what is exactly the problem. More than likely with 75K miles it is a combination of both the bearings and the oil pump.
With 40 psi at redline, if your bearings aren't worn they soon will be!!
BTW, what weight oil are you using? Is it petroleum based or synthetic? How long has it been since your last oil change??
Pennzoil Synthetic 5-30, brand new or old, same deal. What caught my eye is the fact that oil pressure fluctuates with throttle application, which was not the case a few months ago. Plus the idle pressure is lower now as well. I guess the next thing to do would be an oil pump overhaul. I'll be sending you one asap.
I used to run the car hard in the mountains up in souther CA, and i'm sure that the bearings took a beating with the stock oil pan.
Thanks!