It looks like that's a desired item by the vintage arcade guys, too, so you might try some of their sites.
Signal processing can allow you to crop, zoom, and otherwise manipulate a signal to fit your desired mask outline, so you could simulate low-scanrate, overscan, and possibly even spherical distortion with a flat widescreen LCD.
All that said, adaptable CRT would be most authentic. I know a bunch came into ETF in Columbus about a month ago, but inventory specifics might be a challenge.
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