daddyal,
I would think what you are hoping for is unatainable. The rated releif pressure is about 1850 PSI. When I checked mine, it was 200 PSI low of that value. Increasing it to rated pressure made a noticable improvement.
To get the loader to lift what you want, would require increasing the pressure to dangerous levels. I have heard of people pushing the pressure to as much as 2000 PSI, but I would not recogmend doing this, and it still would not get you to the lift capacity you are looking for. If you need to lift 650 pounds, you need a bigger tractor.