it's just the bottom right corner that's different, right?
what pcb is it? are you sure the layout is supported? the white board is slightly different than a 60% with split right shift. (right shift is to left by 1u) with (2) 1u keys to the right of right shift (usually there's only one)
what pcb is it? (supported layouts)
what plate is it? (supported layouts)
need a little more info.
so this is the layout you want.
and this is what the plate would look like for this layout
you can see a couple areas that would need adjusted on the plate IF the pcb supports this layout
here's a quick & dirty overlay
suggest dremel tool with cutoff wheel & some files.
or you could also put it together without the plate, stabs are pcb mount anyway right? looks like a standard tray mount (pcb would mount to the bottom of the case.