I think it is not worth the effort to use the cheap chinese chassis with the Euro TV tube.
I have travelled this path before, over 5 years ago. I bought 4 Chinese Wei-Ya 1820R (iirc) clones to use with some cheap 20" Chinese CRT TVs I'd obtained new-in-box, but couldn't RGB mod (they have an all-in-one jungle chip that incorporates OSD functions internally).
Anyway, the clone Wei-Ya chassis worked well enough with the tubes I guess, but the high voltage regulation was for ---steaming pile of meadow muffin---. In particular they never handled fast bright/dark changes very well, "blooming", there seemed no way to improve it. I tried several tubes, but it just seemed to be part of the design.
So I gave up on the Wei-Ya clones, they were pretty mediocre. Went back to using the tubes with their original TV chassis (the officially called "China TV" chassis, I ---steaming pile of meadow muffin--- thee not), as these are actually pretty good for what they were.
This experience is part of what prompted me to work on developing the GreenAntz RGB -> component transcoder project, because component-modding these TVs was easy enough, but RGB-YUV transcoders were expensive then. Ironically, now you can now buy cheap Chinese ripoffs of our oldest transcoder prototype designs, but they have the same issues as our earliest prototypes too. What can I say
Anyway Haynor, I reckon you might be better staying with original SCART TV. I've used plenty in arcade cabinets before. The Euro TVs are usually be higher quality than most. It is RGB already, and the SCART connectors are easy to hack. You already have the right voltage there at the wall. If using CRT_emulator, it should be possible to customise your monitor presets to minimise overscan and adjust position somewhat for most modes. Often helps if you can access TV service mode, but not always necessary.
Oh yeah, and if using the Chinese chassis you'd need step-down ISOs for each monitor... or a step-down AND an ISO... so add that expense on top, and don't forget increased power usage (put your hand on top of the ISO after it's been working for a while, to feel how warm they get).
Reconsider trying SCART again, and maybe trimming monitor presets (or using ArcadeOSD) to minimise overscan etc. I can give you some pointers if you need.