The rod from McMaster should be ok for this application as they should be sourcing the name branded stuff (probably the same exact stuff). I don’t think there are different grades of Delrin but haven’t really dug into it recently.316 would be a nice upgrade if the cost isn’t crazy, but there will be very little salt getting up there to hit the sleeve so any meaningful additional cost may not be worth it.
Good looking project Tristan. The upgrade probably would be a waste for me and my grandma driving and I think my subframe is different, or else I would add my name to the list also.