Yeah ... I'm about to do the same. Looks like pulling cams to check all components is necessary because of the unknown. I wouldn't buy used parts. Gonna try source shims and buckets tomorrow. I'll Let you know what i can find.
On mine Cylinders 2,3,4 have valve clearance problems. Pulled the front valve cover off and checked all clearances. Seems like cyl 2 and 4 have problems on one exhaust valve only. Zero clearance. What I've read is that carbon buildup will start to drop in and plug valves, seats and guides. The valves will start to stick and deform the buckets the shim sits on. This causes really bad compression issues. Valve will not fully close now. Not an easy fix. My car has been lady driven for 287000 km. Floored it one night and all that build up screwed everything up. Let me know how it works out for you.
