Roll-based AP of same functionality as STEC-30

I'm putting together a proposal for my club to replace TCs with electric AIs
over time. But for this to work, we need an autopilot that can connect to
the electric AI (therefo roll-based). I found a new Chelton that looks
quite nice, but is likely overkill (in terms of price and function) for us.

Can anyone recommend a basic two-axis unit that takes roll input from the AI
instead of the TC?

If anyone has any other comments/suggestions about this plan, I'd love to
hear them (even if it's pointing out why this is a bad idea). One thought
I have is the level of resistance to tumbling of an AI vs. a TC.

Thanks...

Andrew