The headbolts in the suzuki G13ba are not TTY bolts, ergo can be reused. however they must only be tightened with a torque ratchet otherwise you may damage the block.
For cleanup of that white crust - scrape it out and apply petro jelly like mentioned.
Overhaul the carburettor correctly, but first make sure the engine is top notch in tune, meaning tappet gaps are good, new plugs, clean PCV, etc - engine gets normal temperature - Once everything is in place then set the carby.