Shouldn't be too much of a problem. BA threads are quite popular with model engineers and were, once upon a time, pretty much a British standard which got all upset by the Unified threads in the '60s, then screwed totally (as we were) by Metric.
Should be fairly easy to get what you need at a machinists' supply or your local machine shop might be able to do them. The one you need is a 3 BA, just a tad longer than the original. Who knows, they might even have a screw that you can alter.
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