First - Ditch the mechanic and do it yourself, with the help of the forum.
Second - Complete a full tune-up. Valve adjustment, timing, cam chain, carb cleaning, etc....and finish your hard work with a carb vacuum sync.
All if this is cheaply done, and will take care of most, if not all rattles.
No need to jump into the engine until all the easy/cheap stuff is done.
Any carb rebuild kit is fine if you ONLY use the soft parts - o-rings, gaskets, etc. The brass jets in kits are typically garbage.
IF you need new jets because yours are completely corroded and beyond use (i doubt it
![Roll Eyes ::)](http://forums.sohc4.net/Smileys/default/rolleyes.gif)
) buy keihin jets from siriusconinc.com or jetsrus.com.