If you can handle the Big Balls, then by all means, get the Big Balls.
Atari Football is a table game, so there are 2 CPs. Each CP is 22" (or 24" I can't recall right now) wide, but clearance issues under the control panel lessen that by 1.5" on the sides.
There is plenty of room on the stock CP (without major surgery) for me to fit a Big Ball, 1 joystick, and 5 buttons, and when I get around to it I will make a custom CP that should easily fit a BB, 1 joy, and 7 buttons.
The CP will have to be sheet steel though. I'm sure it's possible to mount this several pound monster under wood, but I'd be very concerned about stability if someone got enthusiastic about their Millipede game.
For modular CPs, I'd make a "classics" CP that had a Big Ball and a leafy Pac-Man style 4-way joystick, enough buttons for Defender / Stargate, and maybe a plateless OSCAR 3 spinner for Tempest.
I'll eventually make a page about the Big Balls, with pictures and dimensions and so on.