Try an 18T clutch bell.
The SC8 has very low gearing - I have an LRP 30 in mine with an 18T bell, and it will still drift.. Could handle a 19 or maybe even 20T I think..
I also run buggy race 21's with a 17 T bell in mine, and they still drift..
I.e, try an 18T bell first..
Something like an Alpha .23 with an 18T CB would be ideal...