That is some impressive penetration you're getting with 90 grains of powder. It should do about anything you need done. I've never shot a deer with powerbelts but have shot a lot of them in the range. I always found them a good shooting projectile in many of my rifles..

I was shooting some 295 grain copper plated hollow points today with 90 grains of Goex 2f out of my Staghorn. They were very accurate although for some reason they were hard to load. It could have been the heat and humidity, or just something else. I normally shoot the 245 grain or the pure lead 348 grain powerbelts.