Having very little success trying to setup various CRT shaders

I've been experimenting with several CRT shaders (CRTHyllian and Easymode) as I wanted something without the blur/distortion/discolouration of the standard CRT filter but getting really undesirable output from both shaders.

For example, I'm trying to apply it to Strikers 1945 on Steam, which I believe is 320x224. The game scales this to a full height 1080p output, which is then scaled by my gpu driver to a 4K display. Both these shaders have the following settings;

texture_sizeX
texture_sizeY
video_sizeX
video_sizeY

I can't for the life of me find anything that works well in these. I either get no effect at all or a horrible rainbow effect/something else that doesn't look like a CRT. Putting 1080p in both gives me a veeeeeerry fine/feint scanline effect.

OK, I've had some success using Easymode with games like King of Fighters 97 (320x224) by using 224 vertical and 224*16/9 as the horizontal for both params. Strikers 1945 still looks like a mess with this same profile though even though it's the same 320x224 resolution! Any idea why?