
First tip: use this forum to host your images. I can't even keep count of the number of projects who have lost their images because the external image hosting service went belly up. Flickr might also decide to cut external links to force people to view publicity on their own website, etc.
Second, if you're going to have four buttons in the lower row anyway, might I suggest to go with the red/yellow/green/blue setup of the Neo-Geo MVS system? It would be less confusing for some people when playing MVS games, IMHO.
I hope you don't play with your right arm in this position when there's another player with you, it might restrict his movements a bit.

Also, do you have an image of the design of your cabinet?