While Samsung abandoned the Galaxy Tab 8.9 long time back, XDA community is still very well supporting it. A developer has released nameless ROM for all variants of Galaxy Tab 8.9 including P7300, P7300B and P7310. The only thing that is not working is HDMI output functionality but other than that, everything is working like a charm. To install you will need to have TWRP or CWM a k a clock work mod recovery on your Tab.
To install, follow these instructions: Download ROM from here and copy it to your device; Boot to recovery; Factory Reset/Wipe Data; Format System; Format Dalvik Cache; Install ROM; Install Gapps and Reboot.
It shall be noted that while the ROM works fine on P7310 but 3G is not working on it.