force carb question

I asked this in a different thread, but the title has nothing to do with the quesion so i thought i try another thread. I have a beer that is ready to keg, and i have a co2 bottle that has been sitting for a year or two. I cannot re-fill the bottle this week so I'm hoping ill be okay. When hooked to the regulator it shows about 750 OSI in the bottle... Is that enlighten to carne and push 5 gallons..? And is it too old? (That sounds like a dumb question... But I've never kegged before).
Thanks.

No problem with the age and 750psi should be plenty to take care of a keg, maybe 2.

I wouldn't be worried about the age of the CO2. In regard to how much CO2 you have left, pressure is not a reliable indicator of how much C02 you have left. You need to weigh the tank. I find that the pressure holds steady until near the end of the tank, once the pressure starts to drop it goes fast and is soon empty. I would expect 750 to go fast, but I also think that you may have enough to carb but perhaps not enough to serve.