Timing change as a means of getting more performance is vastly over rated..If an engine would run better with more advance the manufacturer would make it that way....Same goes for larger carburetors...A BIG carb will sometimes help, usually not worth the effort..My G26s run almost the same with a little 3/8 carb as they do with the too large (IMO) stock one...
Move it against the direction to advance, with rotation to retard..You will likely see little, if any, difference...Been there