This one I used is back in stock.

https://www.amazon.com/gp/product/B08YZ2XH5T/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

You'll have to do the ribbon cable on your own, but this one is slim and barely protrudes from the backbox ledge above the playfield.

I would definately use a widescreen monitor. DMDs are 4:1 ratio, so it would probably look off if you used a 4:3 monitor.

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Edit - it says in stock soon, but delivery by July 6-15