the top end can be done with out taking off front fender, remove fuel tank,remove hardware at floor board l&r remove front rack and loosen brush guard, push fender up out of the way you an use bungee to hold it . when timing your cam make sure the auto decompression pins are seated and the timing dot is to the top, if not it will sound like your valves are out of spec. if there is alot of time on the engine i would suggest a timing chain, those old 600 would wear them out fast.
