This afternoon I fitted the Suntour derailleur. Cabled it up, adjusted, and it downshifts perfectly - but the gap and size difference between gears changing up are simply too much for it. Exacerbated by the fact there are no cable stops.
So after due diligence - it's now running single speed on the middle cog. I'm happy with this too, Rat-a-tat dontchaknow.
Tension adjustment works with the horizontal dropouts.
The other impediment to gear changing is the axle is slightly bent (I think) - because the freewheel does the orbital thing worse than just being threaded on.
But this will work Jim Dandy. But I might get a bling-er chain.
Another upshot is I would have put the decals in the wrong spot If I persisted It's gonna be scary fun for a while.
I might try and restore the Simplex derailleur down the track - but I still don't think it would work.
Looking good! Really like the design of that rear axle assembly.
Shifting would probably be better with stops and less housing to compress. Compressionless housing might help as well. Gears are a nice feature on a heavy trike.