Actually replacing the guides on the V-8's is fairly easy, once you have all the accessories and their brackets removed. The chain stays in the block, you only have to mark the chain and sprocket on the driver's side, then remove the sprocket from the cam. Removing the sprocket allows access to the lower guide. Guides are held in by pins, removing the pin requires a special tool, or a proper sized bolt, a stack of washers and a socket (or similar sized nut).
Personally I would remove one valve cover and look at the guide to see what color it is. The guides are white when new and change color as they age. Yellow to light amber is probably still OK but getting close, beer bottle brown need to be changed ASAP.
The full procedure has been covered several time, some with pictures.
Showing the difference between old and new.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.