Valves are easy to do. Did several times on Benz 220D and 240D that we had. On those, I could just rotate those big engines with the cooling fan. Better if you can get a socket on the end of the crankshaft. Just be sure and do it the right direction.
Just check clearances at top dead center. Firing order should be available somewhere so once you find one at top dead center, you'll know which one to look for next.
Just remove the valve cover and use the proper feeler gauge.
Only problem is if an exhaust valve gets too tight. Never saw it happen on the 220D or 240D. Burned a valve on the 240D after it was stored for 4 years, probably due to rust on the valve or seating surface.
Ralph