For those interested I went to an LPG wholesaler and bought something they refer to as a safety switch. Much like a tachometric relay except it doesn't have a starter output.
It activates for approx one second initially and then re-activates when greater than 60rpm is detected.
I went to a Bosch electrical supplier and asked for a tachometric relay. The "cheapest" they had was for $275 for an old BMW. The safety switch was $35. SOLD!