Default Help with Virgin Mobile SII SPH-D710

Hey, a friend of mine wants me to flash a custom ROM onto her Virgin Mobile Galaxy S2 SPH-D710. I'd like to get CyanogenMod onto it, but I'm open to others as well. Unfortunately, I'm not very experienced with rooting/fighting. I successfully downgraded, rooted, and flashed my Verizon Stellar to jellybean, but I can't find a good custom rom for it, so I kind of know my way around.

If you guys could point me to the right rom and a simply put guide for this phone (I don't know if I should use i900 or sgh-i777), it'd be greatly appreciated.

And unrelated, is there any hope for a Verizon S III downgrade soon?