Tkg, those were the mods I were thinking of. [&:]
1) Tap that hole and put a screw in it.
2) Larger carb and big bore manifold. I've seen one of those online engine conversion shops carries a "big bore carb" & "big bore manifold", so I'll see exactly what they offer. I won't buy the largest carb I see because then the engine will be impossible to tune - just as well as you won't buy the biggest tyres in the shop thinking you'll have more traction and grip.
3) I'm really wanting to try the electronic ignition. The weight savings are very appealing, and the speed range should be improved noticeably.

Maybe in the future I'll try more complex mods, but so far I think that will be enough.
Thanks for your tips guys!