Stevo,

You should be careful using the stub wrenches because you might not get the lock nuts tight enough and they might come loose and the valve fall into the cylinder. You might do the final tightening with full length wrenches. I don't have any problem doing valve adjustments on my '79 and '80 300SDs with regular non modified straight wrenches.

Valve falling into cylinder happened to me once on a 220D ( I didn't do the valve adjust job) and the valve , piston and rod went out thru the bottom of the oil pan. Engine still ran on 3 cylinders but of course there was no oil pressure and I knew it wouldn't run long so I shut it off..

P E H