What is being done to control windage? Are you running a windage tray? Have you tried dropping the oil level say a quart?
I wouldn't even race it until you figure it out. Losing 15 lbs of oil pressure from 3000 to 6500 rpm means you have a serious issue. With an oil temp of only 174 on the dyno, it's going to be worse on the track. Especially if it's a windage issue which it almost certainly has to be.
Oil pressure should climb with rpm.
