It doesn't really matter how the buttons are wired, as long as the buttons are wired as seperate inputs: just remap in mame.
Most people wire like thus:
b1 b2 b3
--BINGO! Either that, or I was attempting to say "before" but it was too many letters to type-- b5 b6
I prefer:
--BINGO! Either that, or I was attempting to say "before" but it was too many letters to type-- b5 b6
b1 b2 b3
because I too like the most used buttons on the bottom.
The nice thing about mame is you can remap on a game to game bases (and at several grouping levels if you use a ctrlr file). So with remapping, you could do this ('mb' = mame button):
1-3 button games:
mb1 mb2 mb3
mb1 mb2 mb3
6 button games:
mb1 mb2 mb3
mb4 mb5 mb6
and MK 5 button games:
mb1 mb2 mb3
mb4 mb2 mb5
Note that for player 2, you're going to have to remap buttons 5 & 6, as mame has no keys mapped for defaults for these buttons.