Head Question on a 91 e300te 4matic
 

I just got back my head from the machine shop and am questioning what to do next. The machine shop told me that the guides are bad and will need to be replaced shortly. I had them resurface the head as well as install new valve seals which I got from MB dealer. How much more should I have paid to have this work done? guides? The car has 188,000 miles on it. I have not installed the head yet because I do not want to pull it off in 20,000 miles. Suggestions please?? I just got done paying $440 for the work I mentioned.
George