This topic is a
GREAT idea, and we need to add more shmups

I'm thinking about Cave games for steam : Mushihimesama, Deathsmiles, Dodopachi Resurrection. And also Psikyo games for steam : Dragon Blaze, Zero Gunner, Gunbird, Strikers 1945 etc.
Let's take Mushihimesama (Steam version)
TL;DR
Nice resolution for consumer CRT TV :
320x240@60Best resolution for "31KHz" CRT Monitor :
640x480@60I had very good results by running this game at 320x240@60 on a CRT TV : no scrolling/tearing problem, picture is crisp and clean.
But I also had the feeling it could be better : Mushihimesama sprites have been redone in higher resolution (Steam port comes from Xbox360 port)
So : for a perfect result you have to find a PC CRT Monitor that can handle 640x480 non-interlaced (480p)
I use this modeline with a Sony Multiscan 200ES :
Modeline "Mode 0" 25.18 640 656 752 800 480 490 492 525 -hsync -vsync
In-game Screen settings are very important.
Screen settings (for 480p)
- Smoothing ON (Really needed for nice backgrounds)
- Zoom 150% ( I had initially some random streched lines/pixels when I put other values for "Zoom".)
General screen settings
- Aspect ratio 4:3
- Rotate Left Roll
- Link Rotation ON
The difference between 240p vs 480p on a CRT for this game :
https://i.ibb.co/pL2NB1S/mushi240p-VS480p.png