Here's a 19" SuzoHapp arcade LCD monitor that accepts both 15.7kHz & 31kHz sync rates but would be more suited towards an upright or cocktail table styled cabinet setup:
https://na.suzohapp.com/products/monitors/49-2604-30NI've seen some arcade operators use this type of lcd monitor with the Namco Anniversary compliation jamma pcb (the one that has a bunch of classic Namco arcade game titles to choose from & is coined up with real quarters or tokens).
You'd then would need an external scanline generator (SLG) device to add the required "scanlines" for completeness. Toodles' SLG works just fine with a 640 x 480 resolution setting to enable the scanline filter indeed. They're listed for sale on eBay under "Vga SLG".
You could use a 9" Sony CRT RGB monitor like the Sony CPD-9000 with it's dedicated 15.7kHz sync rate + the obligatory scanlines are included as well. Much better than going with an lcd monitor setup if you want that classic retro crt monitor aesthetic vibe.
PC Engine. Fan X! ^_~