I need to know how many HP the stock Merc oil cooler can be handle?

I am arond 700-750 HP now with upgrade aluminum head and b&m 250 blower at 9 psi of boost.

So the problem that i have is my oil pressure drop from 60 psi at (130f engine temp) to 50 psi after hard run at 155f engine temp and at 5500-5600 rpm.

I think that is because the cooler is too small

Any thought about this would be appreciated.

Measuring the oil temp is the only real way to know. Use an IR temp gun and take a reading from the oil pan.
A 10psi drop in oil pressure after a hard run is normal.

all the oil lines, cooler, filter adapter need to be upgraded to handle that HP, merc stuff is pretty much junk...run all 1/2 fittings and #10 line...