I would recommend at least mod 2 as they are more forgiving if they are slightly mis-aligned.

Velocirippa runs smoothly on mod2 gears. Mod1 gears will work OK but you need to be more precise in siting the drive axles, it is not as simple as it at first appears. It will also fit into a smaller space than a gear drive.

My other m/c, Mighty Mouse, has homemade gears. I know from experience that your drive train needs upgrading(heat J semis)

And yes I will be at Portsmouth may 8th and you can have a rematch, gladly

Any more questions about gears e-mail me

Cheers - Trev