Having had more details of the requirements I would say that the problem is MUCH simpler than it seemed initially. There are many, many, companies that will modify an existing case type.
It would definitely be worth contacting Mountain Mods in the USA as they could make you something very simple from their existing CYO sheet construction system. A Mountain Mods Monticle 24 could be built with the front effectively upside down (5.25" drives at the top, fans at the bottom) and the power and reset switches can be mounted anywhere you like. It won't be under £250 delivered with all taxes paid though, but it's definitely an option.
The silverstone TJ-07 also has several companies making modified panels for it - Cold Zero, Akrylikustoms and Murder Mods immediately spring to mind. Cold Zero could certainly make you an upside down front panel for a TJ-07 with whatever switches you want in it. And used TJ-07's are really cheap assuming you have the desk space for something that large.