CyanogenMod 7 for Samsung Galaxy S II may not be the most stable ROM. It is still in nightly development stage. But due to that, you can try the latest Android 2.3.7 Gingerbread GWK74 on Samsung Galaxy S2 now. And it is using XXKI3 baseband from latest official firmware.
cm_galaxys2_full-72 build was the version that I tested. It is based on Android 2.3.7 Gingerbread. I believe all the future build will be based on Android 2.3.7 too. Hopefully, CyanogenMod 8 with Android 4.0 Ice Cream Sandwich will be coming out soon…
Note – This is a nightly development release. Do check out CyanogenMod website for latest build.
Installation guide ~ How to install firmware on Samsung Galaxy S2 with ClockworkMod Recovery?