If you are building a mk3 for the sake of a mame cab then you can't use the original button layout and therefore can't use a nos overlay without it looking like a hack job. With that being said mk cpos are very organic and therefore can't be fully vectorized. Probably your best bet is to buy a nos cpo, scan it in, edit it or have it edited for a sf2 layout and then get it printed.
I wouldn't go with a mk3 design btw, mk2 looks waaay cooler.