The best battery for a UPS is a deep cycle one. Or a battery that has slightly thicker plates as compared to the normal engine starting batteries. When the OSAKA IT series batteries were introduced in NOV 2008, the advertisement mentioned that they were using special thickness for the +ve and -ve plates. They even mentioned the thickness in mm. I checked and compared it with deep cycle batteries and they were slightly more than the lower limit mentioned for a deep cycle battery. They were however thicker than the one used for starting batteries. That is why I went for the OSAKA IT-1000 battery. The battery is working fine up till now. Although it is not a true deep cycle battery, but still it is better than a normal starting battery.
I have not done any research for batteries after Jan 2009, so I do not know if a better alternative is available. About the OSAKA UPS batteries, the ones available before Jan 2009 were just normal starting batteries with new labels. I do not know if they are still the same. You can call VOLTA and ask if these have thicker plates or not.
If I was shopping for a battery today I would have gone for OSAKA IT-1250 based on the performance of the current IT-1000 that I have.
I mentioned a calculator in post#155 on this thread, use it to calculate your battery run time. Make sure your battery run time, with your specific load, is more than 2 hrs. The more the better, as this will ensure you batteries will not discharge below 50%. This will keep your batteries in good health and they will last a long time.
I would get two 140 AH batteries with your setup.
I hope I answered your questions....