To the best of my knowledge, you cannot buy those caps from Ingersoll any longer. Other brands did offer caps for their tractors (Deere, Cub) but I am not certain that what they used is identical to what Case used. Last year at this time, there was an advertiser on MTF that was selling repro caps for Deere and some other brands such as Horse. I don't see him there any longer. Perhaps if you asked on the Deere, Cub and Horse forums on MTF if anyone has contact info for that person, that would be a start. I wish you well in your search. If you should come across a source, please return to this site and post what you found in this thread or create a new one. I'm sure that some other Case owners would love to have a new set of those caps, front and rear.
Sorry I'm late to this I just saw it, I have a pair of the rears that I have to have rechromed for my 130 - they are not the same as the ones other makers use because there is a notched/dented area for the valve stem.