I have a fat front tire cestad trike like yours with the single seat,tho.
(Mine is the MW version)
The original hm80 had the lightinng coil like yours. It did not have the ring gear
For a starter. I found an AC 120V starter and a ring gear flywheel from a later
HM80. I was unable to find a 12V starter so I put the AC version on it.
So, could only start in the garage!
However, I eventually replaced that HM80 with a late model NOS Tecumseh 11hp, ring gear
And 7 amp lighting coil. Stuffed a battery behind the seat. Wired it so that that the
12v output goes straight back to the battery. Works great.
My problem was that the HM80 had so many flywheel/starter/lighting coil variations that I
Just couldn't find the right combination for the 45 year old motor.