Any advice about what to look for when viewing a Jawa (two stroke) 350?
No reason... 
GC
WHY !!!
You have more than enough Rubshh !.....Errmm Stuff !

Too Old...cant get the spares as easily OR cheaply as you could !
Having had a few they go supprisingly well,very torquey.
Hope its 12v electrics....where would you get the points from nowadays ?
An outfit I had pulled myself,robG,a slab of beer and camping kit to The Dragon back in '94 at a steady 60.Stopping was a little entertaining.
Capable of crossing a Ploughed field with ease.That was the alloy engined TS350.
And I really liked my CZ 350.Cracking bike.Basicaly CZ 125 rolling chassis with the Iron Barrelled Jawa 350 Motor in it.
Jethro