I'm not sure what the op is planning, as he seems to have a stand-up cab right now, but I'm thinking of a dedicated sit down racing cabinet. I already have two matching car seats.
I don't think it works too well on a stand-up due both to ergonomics and frankenpanel-dom. There was a thread recently where someone picked a factory stand-up racer, and he said it was extremely uncomfortable standing for long play sessions, and chair/stool ideas didn't work too well either as the pedal to wheel spacing is meant for standing up. I've played stand-up Cruisn' cabs a few times, and I can totally see it.
Maybe it would work if you made a large assembly you could roll up that had a raised seat, with appropriately positioned pedals and such. If you got really creative, maybe you could make it fold up for storage. Otherwise, if it's a solid assembly you might as well slap a monitor on it and have a separate cabinet.