Quite a few members here have used G&H. They know their stuff and do excellent machine work. They offer and use only the highest quality brand name piston kits available. They remind me of the old-school craftsmen machinists that are almost all dead and gone nowadays. They take no shortcuts... You'd be hard-pressed to find anyone more skilled and capable than they are. Call them up and talk to them, they are very helpful folks.
You can do the topend and timing chain job while the motor is still mounted in the frame or you can take the motor off and work off the bench. Do it the way you are most comfortable doing. I personally prefer to do the work off the bench cause I'm an old fart with a bad back, junk hands and failing eyesight. In my early days I'd always bulldog it... nowadays I can't. Its your call....
You'll need the FSM and common metric tools to get the right side cover off & the topend apart, and a decent impact gun (air or electric) with sockets to get the clutches off, so you can remove the oil pump to swap the camshaft chain out.
Precautionary tip for ya:
I've done a lot of topends over the years and every now and then while I'm lifting the cylinder off from the cases on a worn out or busted up motor, I've had broken piston ring chunks or other junk fall out as soon as I lifted the jug up clear of the rings and the loose piston falls over.
Before lifting the cylinder jug from the crankcase, rotate the crankshaft so that the piston is at the top of the bore (TDC). Get a handful of clean rags or towels ready and begin to slowly lift the jug until the piston skirt is seen clearing the bottom of the jug. Hold the cylinder right there, don't lift it any further... and stuff your clean rags in real good and tight all the way around the connecting rod at the top of the crankcase, so that if any busted piston ring chunks, loose wrist pin circlip, busted piston ring lands or whatever... can't fall into the crankcase while taking it apart and while you are working on it... and ruin your entire day! Leave your rags in there until you are sliding the jug back down on reassembly with all new parts.
I've only seen it happen to someone (not me!) once... don't forget to remove those rags altogether before you drop the jug back on.
One of the clutches have lefthanded threads and the other clutch has righthanded threads on the nuts holding them on. Both are staked down from the factory. You can use an Impact gun and zip them both off without unstaking them first, no problem. Just don't try to take the lefthanded threaded nut off, thinking its a righthanded nut... & vice-versa...
Another very important tip, this one is critical to your success!
When you get your cylinder back from the machinist, Scrub it thoroughly inside & out with HOT, SOAPY WATER and stiff plastic scrub brushes. The freshly honed bore (if unwashed) is full of machining grit and honing oil. If all that junk is not scrubbed out of the bore it will chew up your new piston rings in just a few seconds on first startup and will ruin the fresh new bore. I can't state this any firmer... Scrub it until you are sure you have it laboratory clean... then grab a second batch of hot, soapy water and scrub it again! Finally, rinse the soap out of it and wipe it out immediately using rubbing alcohol to remove the water quickly. Then put a bit of CLEAN motor oil on a WHITE paper towel or cotton rag and wipe the bore with oil real good. Look at your wipe when finished... is it stained at all? If your white wipe isn't still perfectly white, mix up another batch of hot soapy water and scrub it again. Make sure you oil the bore immediately following the alcohol wash to prevent it from beginning to form rust.
No worries, its not difficult work... just thoughtful and thorough work... Have fun with it!