Configure custom resolution mode

I’m using hackintosh. I want my things on display be sized as I want them. I found that of existing resolutions of my 27′ display I like 1280×720 the most
But of course for the 1920×1080 27’display it’s too blurry. MacOs only supports “HiDpi scaling” which is: I have to create 2560×1440 (twice the one I need) resolution. MacOs will then render everything in that HQ resolution and it’ll be sized as I want it. But I can’t figure out parameters for the 2560×1440 resolution. There are methods of auto-calculating it as far as I understand such as CVT, CVT-RB but I don’t know which one to choose. I believe the vertical scan rate should be 60HZ…
(through HDMI them monitor uses 67KHZx60HZ for 1920×1080)

Also, if it’s connected to this topic: for unknown reason that “HiDPI 1280×720” is only listed as supported in VGA mode. But in HDMI mode the maximum listed is 960x540HiDPI (it’s that “maximum supported by monitor 1920×1080 scaled as you see”). Is availability of 2560×1440 through HDMI connected to the aforementioned “porch” and other parameters?

PS: on windows I simply use 1920×1080 and either 150% or 175% scaling) And it works flawlessly THERE ( (but not here under these circumstances ) So I believe basically I’d need (1920/1.75*2) 2194×1234 but it’s not among listed monitor/gpu modes:

UPD: So if I use:

the screen has unproportional black borders On the left is wider then on the right and isn’t properly scaled.

And If I use

then it doesn’t work at all (monitor skips vga)…