Plugs were black and sooty=rich; there was some red silt/sand type debris in the floats. Filter was clean, not rust, tank is clean; possibly some kind of cleaning media?
Anyhow, the bike runs great without surging.
Thanks for all of your help. If it wasn't for the debris in the floats (for which I have no equipment or space to properly take apart and clean carbs with), I'm confident I would've got it to run right with all of your help