Thanks again @matze79 but I think I gave up. I tried with SciTech drivers, 5x, 6x and 7... No luck neither. The MSDOS driver says no compatible SVGA display chip is found, when I try and run manually VBETEST in version 6.x I can see it can correctly display the color and patterns at 1024x768 and 16bit colors so it can clearly handle the DAC but I have no idea how to go and tell it "hey, I know you don't detect a compatible chip and all that stuff but believe me, it works" and then from there tell Windows to do the same...
This hobby is getting harder than I expected 😁