The holes are the same as the inside holes on the Happ sticks. Japan / Europe use the narrower mount.
With the stick removed, the top of the base is flat so it is easy to use it as a template.
I have a T-Stick Plus for player 1 and a Happ Competition for player 2. I drilled the holes for the T-stick on both so I can use either stick. All of the Happ sticks I have seen have both sets of holes. Original US arcade sticks do not, they only have the wider spacing.
Hope this helps,
Paul