Wellp, 6'4" ain't too shabby!!
At 6'8" I have to kick out my right knee to run the skinny pedal in our Yukon, we have a 1997 because after the OBS left, every SUV has a huge center console for some reason. I also know that having a passenger's knee close to the dash means that the passenger stays in place in an accident. We looked at the 4 door Jeeps when they were new but my knee was shoved into the console and dash beyond comfort.
In my 1992 XJ I moved the seat back as well, I looked at fabbing a bunch of bracketry but finally just tried moving the front seat frame mounts to the rear floor mounts. Turned out to be about 12". It was almost too much but I was able to press the clutch all the way down, but nobody else could hardly reach the accelerator! I simply drilled two rear seat mount holes in the floor and nut/bolted them. Those mounts were pretty flat and so was the floor, not sure on the Burbs yet as I have seen another member here that mounted a floor jack under the passenger seat (below the truck), and at first glance it looks like it is raised higher than the rest of the floor. Also consider that if you move the front seat back then you may not be able to fold the second row forward, I know our Yukon has to move the seats slightly forward from fully back, to be able to get the second row folded flat.
Here is a picture of my XJ seat fully forward after I moved the frame rearward and remounted. When fully back in the frame I could strech out comfortable enough to sleep in the drivers seat, however it was a 2 door so it had more room than the normal 4 door model to begin with.
You may also notice that I had to extend the shift lever about 6" with a long bolt and a stack of washers!
My wife never drove the XJ but consider if anybody else may ever drive the burb that has little people legs and can't reach the pedals even with the seat fully forward.
Snap a picture of the front row seats if you get time, I am curious about the "custom" center seat and console you mentioned?