Things needing to be adjusted after removal of head (M103)
 

What type of things should I have to fiddle with to get the engine running at OEM specs?

I believe I found the cause of my misfire to be shot valve guides causing the valves not to seal completely.

On rebuild of my head, what will I need to go over to ensure everything is running to Mercedes specs?

Timing?
Fuel Air Mixture?
Anything else?

Not a lot of fiddling to do on the 103 engine. The timing is fixed and read off of the crank so you never have to worry about it as long as there is spark. It would be worthwhile to check out the cap and rotor closely. Also inspect the rotor adapter closely for hairline fractures. Don't crank down on it's bolt either, it doesn't bottom out in the cam and too tight can stress it and crack it in the future.

If your mixture was good before the head job it should be good afterwards. It's a good idea to check and adjust the lambda after any major repairs but it is unlikely it would take more than a minor tweak. You should check your hoses and lines closely b/c it's easy to break brittle stuff in the process of removing and installing the head.

Fill the block with antifreeze before installing the thermostat. Completely assembling the cooling system and trying to fill from the reservoir is going to be a slow, aggravating process.

Get the engine hot before allowing any pressure in the cooling system. The gasket actually cures and swells the first time it gets hot. Until then it shouldn't be considered 100% leak tight.

Thanks for that.
I thought that the timing had to be lined up to something in the head?

Rotor + Cap are brand new, same with all hoses.

If you have the manuals, in job 01-450...
 

Look at steps 22 (Positoning bore of camshaft is aligned with the marking on the first camshaft bearing) and 23 (Position piston of cylinder 1 to TDC).