Ok, so you don’t want to use the premade images on the download page. This distribution come with premade perfect centered resolution. You go here the hard way.
WARNING, again I would recommend to use the retropie distribution on the strike devices download page. It should give some good resolutions for you. If you want to go the hard way, then this is for you hdmi_timings=256 1 8 17 21 224 1 7 10 24 0 0 0 60 0 4800000 1look at the red numbers
x1 = 8
x2=21
if you want to move left by 2 pixel, then
x1_new = x1 – 2
x2_new = x2 + 2
moves on direction and the other this way
x1_new = x1 + 2
x2_new = x2 – 2
For Y go with this numbers
hdmi_timings=256 1 817 21 224 1 7 10 24 0 0 0 60 0 4800000 1