OWD is totally correct in this matter. Best is best. As an aside, although I've never done it, I've wondered at the possibility of taking about .020" off the pin, reducing it's diameter .040" and then fitting a hard steel sleeve over the pin. The machining work would be less tricky. Making a new pin, if you want perfection, is very time consuming. You want the threads to be as tight as possible, likewise the cap and while the old pin is a guide, chances are good that it wasn't perfectly fitted to begin with. You want your new one to be better. Lastly you have to drill and tap for the screw that goes in from the knuckle and this is a blind hole. If it's an older Brit gun all the threads will be Whitworth, another "pita".