I am thinking there is another approach available to you. Start out with some O-1 material soft take your time and cut as close as you can with your hacksaw. (I try and teach my apprentices how to use one very early, and when they can cut a straight line I tell them they are in the 1% of the population that can, remember don't force the blade, and use a sharp blade, and it only cuts forward, LIFT on the back stroke!] then you can using a file bring it home. Again the file only cuts forward, Lift on the back stroke. This will be an incredibly slow process, but should create a real sense of pride when finished! The ball detent is a little more complex in production, but drill the hole undersized and again with a lot of patients raise an edge by peening then drill the right size hole to depth, [drill press or by hand with an electric/air drill motor] Heat treat the pieces with your torch and dunk in a medium sized can of oil.
There are special oils that won't flash [Waste oil from your vehicle maintenance (mixed is good too) will do the job with some precautions] but you will be using tongs and gloves, make sure it will not overflow especially while on fire! Duh! I know but I am really telling you what can and frequently does happen. Don't be greedy do one piece at a time and let the oil cool all the way down between parts.
Your pieces should be at or near 60Rc [Hard as #ell] The black colour will need to be removed so you can now heat the pieces to a real light straw colour and let cool SLOWLY! [this will mean with parts this small, put them in your self cleaning oven immediately after a clean cycle and let them sit in the cooling oven, or place them on a small hot plate and dial it down over about 15 minutes while covered] This should land you in the low 50's hard but not very brittle. The raised section around your ball detent hole you should heat this up with a little torch [micro torch] and let this cool this should soften this to the point that you should be able to peen this back and capture the ball. You will need to create a couple of punches for this one with a countersink to push your standing burr over to edge and then a centre punch with a relief for the ball to create the factory look/function. You should practice with some small scraps, as that detent may require two or more "Draws" to get soft enough to not crack and break off. that edge will cool very quickly and may not soften much with each heat cool cycle. this will cost you about fifty$ in material and about 50-100 hrs of your time. I would scour eBay/C-list for a parts unit myself now but I have done this [my unicorn projects not a ratchet] when time was plentiful and money not so much. Hopefully some metallurgist or heat treater here will interject some numbers that you can use with a now available I R Thermometer, I was taught this with a person showing me the colours, so internet translation may be harder to grasp. Harry P.S. you can use the appropriate machine tools you may have access to.
