I find the A/B Chorus a great derailleur for friction shifting. I haven't experimented with it in an indexed situation.

I think indexing C-record was in the Synchro system and possibly Synchro II, right? One possible exception could be that the C-record styling was used on some Record 8-speed cassette rear hubs with 130 mm OLD. I'd assume that hub is compatible with 8-speed Ergo levers. This still doesn't say anything about your rear mech. I'll go out on a limb and say that it your rear mech isn't slant parallelogram, it's not going to index well, even with all the other right compatible stuff.