I see what you mean. It shouldn’t be a difficult job to recut the threads or rebush for available screws. If you can find screws from a M-1911 and they turn out to be slightly larger in diameter you’d only have to ream out and retap the threads. The Model B is basically a metric copy.
gunparts corp should have everything you need. And for goodness sake, how many different gripscrews can there be?