Use Lightspeed II+ for RPM data on AF2500?

I have an ACS2002 (now known as AF2500) by Advanced Controls Systems. My RPM display is often a little erratic - it varies by 20-40 RPM in flight. I don't think my actual RPM is varying like that, I think its the reading I'm getting from the Magneto sensor.

I thought about trying to use the RPM output from the Lightspeed ignition instead of the magneto based sensor. Has anyone tried this, or know if it would work?