Even though the R and GTI seats are essentially the same, there's a different potential benefit to the R for the OP: the R sold in the NAR does not have a sunroof, whereas many GTIs are so equipped. For a 6' 7" guy that's going to make a meaningful headroom difference.
That said, my son is also 6' 7" tall and probably pushes 300 lb. Finding a car that he fits in comfortably has always been a challenge. He's ended up driving a long line of Jeep Grand Cherokees. Yeah, not nearly as fun as the R, although if you don't mind an EPA highway rating of just 17 mpg, the 707 hp Grand Cherokee Trackhawk would probably deliver more than a few laughs! On the other hand it costs more than a pair of Golf R's.