WTB GS head (CA)

[gturtle30]

So, here's what happened:

A couple of months ago now, I was decelerating at a light (engine braking) on my '89, when all of a sudden my engine starts throwing a fit of noise at me.  The loud clattering sound (about engine speed) prompted me to pull into a parking lot where my bike didn't start again and just made a horrible noise when it was trying to turn over.  I opened the valve cover thinking a shim might have worked loose somehow, but to my dismay, I found nothing out of the ordinary, just that the cam chain advanced quickly and with a loud click whenever I advanced the engine past a certain point.  I took it to my local mechanic, and his flashlight down the spark plug hole revealed that my valves are now opening concurrently, hooking on each other as they reach full depression. 

I assume my cam chain was too loose (or tensioner wasn't working), it slipped, and now things are all out of sync in there.  I would guess that the valves and valve guides are going to need replacing along with the chain and probably the tensioner, but figured that a good top end swap would be actually less intensive and more doable at home than actually replacing the valves/guides.  (The bike mechanic quoted me a bunch of money since cracking the engine costs an arm and a leg in labor charges at the shop.) 

So, I'm looking for a relatively low-mileage, good condition cylinder head (or even whole engine, at a good price) for my '89 GS, and welcome any advice on the best course of action to start getting my baby running again...

Thanks and ride on,
J