There are no specs for what you're looking for in the factory repair manual. I looked in some PROSIS software (it's what machine shops use) and it said (I'm going off of memory here) something like .050 to .060" valve recession. I knew this couldn't be right because my valves were all less than .020" below, with most of them closer to zero.
I took the head down to my local trusted machinist, and he agreed with me that the PROSIS specs could not be correct. He then looked up specs for a 172" diesel, which is the 4-cylinder equivalent of the 242 diesel engine. Again, I don't recall the exact number, but it was much closer to flush. He used the 172" specs (he had to replace some seats) and everything worked out great.
I can look up the exact numbers for you the next time I'm at the shop, but any good machinist can look them up in PROSIS as well.
By the way, FWIW, there is no "Commander" repair manual that I am aware of. The differences between Commander tractors and the older ones are primarily cosmetic. Many of the pages in my manual date back to 1961 and 1963.