Jack's method would work well, no question, but it does involve a good bit of highly skilled and patient work.
There is a simpler, albeit lesser quality, of 'improvisation' which I've done on the similar driven pulley of a Delta DP220. That one had multiple areas broken away from its lower V flange. This was to simply remove that lower flange, and accept having only the three higher spindle speeds, which had that little drill press being entirely adequate for woodworking use, and good for 5/16" drills in steel. (I later traded that DP220 off to a woodworker, and kept only one of the little Delta drill presses, a slow speed version, for my own use.)
It would be quick and simple to hack-saw away the lower flange, and file the remainder of the pulley to a uniform height, to keep it in balance, as nearly as might be.
There are a lot of older small machines, from the era of American high quality production, which are being restored for practical use, these days, when the only alternative is horrible low-quality oriental 'joke machines'. Someday, somewhere, someone with a small machine shop business will be offering to make short runs of parts like that pulley, most likely cast in a good grade of aluminium instead of that horrible zinc alloy. Its an easy turret lathe job, once a setup is made, and broaching the spline is quick and easy, to be sure. The only feasibility question for that specific part is the first cost of the broach itself.
(there is quite an opportunity here for the right person......consider Mr Scott's operation in providing the parts to restore old vises to serviceability)
cheers
Carla