Well guessing is all sorts of fun. I have found after setting up new bikes and old alike that the first order is a teardown and time to see what is in the rig already. If the PO has been bandaiding the over rich condition like you are hinting you were thinking of doing, it may already have smaller jets in it than it will need once the float is set right. So if he had jets in it 2-3 sizes smaller than stock, get some that are within one size of stock and put them in it before you ride it. Do some plug tests etc. The float level always raises if left on it's own. If it has already been leaned out to compensate for that, you may seize it by putting the float back to where it was suposed to be to begin with. The main jet is easy to get at without removing the bowl and a good place to start to see if you need to shop before you go any further.
Tapping on the bowl may have done the "trick" but it didn't fix anything. Floats dont' stick as much as they get garbage in them. You can shake it out sometimes, but it is still there. Next stop for it will be in one of your jets. If the float needle and seat are worn enough, tapping may get them to seat together better, until you fire it up again.