Peter – horses for courses. One has to be careful because I have no idea wghat the loads on clock pinions are, but given that a lot are made of brass (I’m no horologist BTW), and last a long time, I doubt the loads are high at all.
That being so, I would munch them out of dear old 220M07, case harden that if I had a fit of enthusiasm, and leave the problem of wear to my grandchildren.
Very willing to be corrected, but most sliding surfaces don’t need hardening. But, if hardening is definitely on your menu, that will harden fine well for our purposes. I have used it for the driving pins on model traction engine pumps delivering at 125 psig, and a file doesn’t even touch the case.
Might I suggest (very politely) that part of this tizzy was caused because the task was not specified. Also be careful – the road ot hell is paved with good intentions, and what might be good in industry for production, might not be necessary or even appropriate or feasible for us with our less expansive resources. Its necessary to keep an eye out for gold plating on occasion.