4 action buttons per player: Guard, Horizontal Attack (A), Vertical Attack (B), and Kick laid out like so:
A B K
G
There are also start buttons for each player.
I think every Soul Edge I've seen was a conversion kit (including the v.2 board I have now. Most I ever played had a 25" standard-resolution monitor.
For many cabinets the dimensions will be on the flyers. Unfortunately,
Soul Edge's flyer doesn't have any.