I installed an XP-360 on my RV-7 with a slick 4371 on the left (bottom plugs) and LSE plasma 3 on the right (top plugs). Unfortunately I only wired the right system into my engine indicator (GEA-24). So I have to wire in my left RPM. I figure I can either attach a sender to the RPM drive off the back of the engine or attach one to the magneto. Any suggestions on which would be the better choice? Thanks.