Cylinder heads are not rocket science...plenty of knowledgeable and experienced engine machine and repair shops...all he needed was specs and dimensions...General motor repairs, like head cutting, cylinder boring or crank refinishing can be done by any good motor shop...Metric Motors...extremely pricey.
I would not agree with "extremely pricey". Good work is never cheap, but there are far too many people today, in far too many fields expecting far too much work for far too little money. All the expertise on a Mercedes ANYTHING comes with a price. I see this all the time in my corner of North Carolina, where people are looking for a "reasonable" plumber, or a "reasonable" electrician or a "reasonable" mechanic because with all the limited inquiries they've made they don't like the prices; they are "unreasonable"; then last week, someone locally here in my area was looking for a "cheap dentist", two words (am I right, @John Mancini?) I don't ever want to see in the same sentence. Skill and expertise are not going to be cheap.
Yes, if a local Kansas City machine shop has the right tools,
and all the correct specifications, surely they can determine if the head can be repaired, and probably repair it. What exactly are the "correct specifications"? Are they the same for all cylinder heads on all M127-M130 engines? Would it be any cheaper than Metric or Noel's or, if in the UK or Germany, the places there? What if parts are needed and this local machine shop has no clue as to where to find these parts? There are literally hundreds of suppliers of all engine parts for American cars, even Porsche has many suppliers. May be a little more challenging for someone not familiar with a 60+ year old Mercedes. I surely don't know the answers to those questions and that's why I would pay for the expertise and experience. Most MB dealers would farm out this work since they don't have in house machine shops. (fewer and fewer have in house body shops either!) Maybe a call to the local dealer's service departments may glean some information on the possible machine shops in the area worth calling. Just tell them its for a very old car they wouldn't service and ask for any recommendations. This is true if you are in Kansas City, Kalamazoo or Kenosha.
We here are a limited subset of "older Mercedes owners" and aside from dealer inquiries as noted above, it may be a worthwhile effort if @Diggerjames made contact with the local MBCA chapter for KC, and started asking questions there; contact the officers by phone. It's a larger set of people with older cars who may have utilized local services. (Note: though I have not been an officer of the Michigan MBCA chapter in some years, I got a call
YESTERDAY from someone in Michigan seeking information on rebuilding a Bosch electronic module for fuel injection!) There also may be members of the 190SL Group or the Gull Wing Group, in the KC area, that expand the pool of possible old Mercedes owners who may have a line on localized services. The calls certainly cannot hurt.
In our group, BTW, in a quick search, we have ONE associate member with no posts in KC, Kansas. We have none in KC, MO. Going "outstate" in both KS and MO, we do have 12 members in MO, 6 of them full. We have 5 members in MO, 2 of them full. Few of them are active thus postings probably won't be seen. So our group by itself isn't going to be a great place to conclude your search. The MBCA also has at least one Technical Advisor that may specifically direct you to people to talk to in the general area. Worth a shot if you are a member of the MBCA. If not you may have challenges.
I think the bottom line is if you talk to enough "Mercedes people" in the area, club members, dealers, etc. you may find one or more local machine shops that you can call and at least talk to. Hopefully one of them will give you the confidence to entrust your head to. If not, you can always send it out.