'nother cocktail cab, CP advice request

[ericball]

Through happy accident, I have in my possesion both a spare PC with TV out and a spare 20" TV.  I've managed to sell my wife/CFO on the idea of building a cocktail cabinet for MAME.  My planned design is loosely based on Kyle's PacMan plans, except with an additional two-player side-by-by CP on the long side.  (Which has been done before.)

Anyway, I am plotting my CPs and would like some input & advice.

For the vertical CPs I will be going with a single Wico 4-way leaf with 3 buttons on each side (my wife is a southpaw) in an inverted triangle.  I figure that will cover almost any of the classic 4-way or button only vertical games.

For the horizontal CPs I will have an 8-way (p360 maybe) for each player with ? buttons.  Question - ignoring fighters, how many buttons are required to handle classic 8-way horizontal (standard res) games?

The player & other buttons won't be on the CP either.

And is 1.25" a standard spacing for buttons?

Thanks