Why would you change the head? Talk about lack of repair capability.
Since you have so many miles I might suggest a valve job including valve guide replacement. If your shop can't do that, get another shop.
Even with your miles, if it were my car, I would evaluate the spark plugs and go for the worse cylinders; replacing the valve guide oil seals. The total job is about 3-3.5 hours and the seals are probably about $20. If while doing the first few "worse case" valves, it is found that the guides are too worn, then the head should come apart.
Replacing seals on worn guides will probably not last another 200k but is so cheap that its probably worth doing from a diagnostic sense. Since the whole motor is old, a cheap patch for 20-50k would give a chance to use up the bottom end before deciding whether to invest the big bucks, motor restoration will require.
Bosch Master, ASE Master, L1
33 years MB technician