Did you say you were there in 1977? My wife lived there until moving to the states in 1982. I don't know if you remember it or not, but there is a compound and airstrip on the left hand side of the main road into Mitla (between the village and the higher mountains). That is the translation center for the Instituto Lingüístico de Verano (Summer Institute of Linguistics). My father-in-law oversaw it's construction, and today heads up maintenance and new construction. He is 77 years old, and acts like he's 50. My mother-in-law (a year younger) does all of the book-keeping and administrative stuff.
When I was first in college I thought of doing something like translating for Wycliffe. Our college group visited them in Mexico City January of 77 but I was sick and couldn’t make it. I recovered by the time we went to Oaxaca (and that Baroque church is quite beautiful). I ended up teaching school in the Dominican Republic and then coming back for graduate school.