Although Man in the Moon Marigolds had a certain popularity back in the 70s, I think it's not anywhere near as well known now as some other plays from the time. And its 1978 Broadway production was a flop, running only 16 performances (although it ran for 2 years off Broadway from 1970-72) .
None of his other plays enjoyed any commercial success. I saw a community theatre production of And Miss Reardon Drinks A Little back in the mid 70s (also flopped on Broadway in 1971 at 108 performances), and remember liking it OK.
The Secret Affairs of Mildred Wild ran 23 perfs in 1972, and Ladies at the Alamo ran for 20 in 1977. He has 4 other published plays that Ive never heard of.
It's hard to imagine why anyone would invest in a commercial revival of any of these.