Well first let me start off by saying that you're not going to be liking those "angled" joysticks (I'm assuming they are by the position of the crosshairs). It's one of those things that seems like a good idea on paper but a disaster waiting to happen in practice ("I'm pushing up, so why is my guy going up-left?").
EDIT: I see that was addressed before I posted...
Secondly, try to break yourself free of the misconception that your panel has to be ungodly huge. I fit a trackball, spinner, 2 sticks and 12 buttons into 25" x 10" of space and no one has ever been elbowed during a game of SFII. Others have panels that are maybe only a couple of inches deeper and/or wider and are spaced out more comfortably. (I will admit my panel is not Golden Tee friendly and having components closer together makes wiring installing a little bit - but not much - harder)
I'm no engineer but, at best, it will look horrible disproportionate and, at worst, will be leaned on too hard and the panel will break off (or, if you secure it nicely - it will only take the whole cabinet down on top of you instead).
So how big is the blue space anyway? Is it too late to take the small cabinet and trade it in for something that's more capable of holding a large panel? If that's not possible, you're going to have to cut down on space (ditch an extra button, push them closer to the joysticks, crunch things together).