what are your specs?  Pipe? air filter? air box? porting? reeds? elevation? gas? ratio? mods? 87 carb or 88+?

If you havent done a leak down test, i'd do that first.  Jetting wont matter if you have an air leak.

And since you're popping crank seals i'd imagine you have an air leak.  Have you tested your main bearings?  grab the flywheel and move it up and down.  If it moves, they're bad and will suck air.

Im not sure about the correct gap.  Are you looking in the repair manual or owners?  I'd imagine it would have to be the repair manual.  I can look tonight if you dont have one.

Also, it would be a good idea to go ahead and test your stator.