Hi!
Never worked with a full size cab, but anyway...
You've got a great profile cab, and one that not too many people seem to own.. (according to klov.com) ..:
http://www.klov.com/game_detail.php?letter=S&game_id=9655 ..? Even though it had already been modified by the previous owner.
On your website you mention that "I can't decide if I want to keep the boxes and make them blend better, or just build a new control panel and transfer the parts..." - I'd say, DO transfer the parts. After all, you already have them and it'd be not that much work anyway ..and won't cost you too much as you wouldn't need but a few pieces of MDF to build a CP.
You've done a great job on finishing the cab! But, if I may say so, take those supports off and build a completely new CP (maybe supporting from the inside of the cab..), after all, there're plenty of good designs to adopt here on arcadecontrols.com .. And even with all the controls you have now, it shouldn't be any problem to fit them to quite a bit smaller panel..?
Not sure if you could fit all the stuff between the actual cab's width but here's one link at least:
http://forum.arcadecontrols.com/index.php?topic=58953.0 ..
Anyway, all the best with the future modifications !!