Android 4.0 ICS in Samsung galaxy R
You can look for a Galaxy R custom ROM on xda-developers section of your device. (Link)

Do not flash the Galaxy S II ROMs on your Galaxy R, or you may end up with a unusable device.

From a quick glance I had on your device's section, it seems that it doesn't have a ICS/CM9 port yet, but that may change.  

Currently only CM7 is being ported. Though since your device is lined up for Official ICS update, my advice would be to wait for it.
See more here - xda-developers Galaxy R Guide