Alfred ‘Ice’ Cole was also a 6-4 cruiserweight champion. At light heavy, Bob Foster and Leeonzer Barber (Kronk guy who held the WBO version for a bit) were both 6-3. Not sure if there have been any taller than these at those weights.
Henry Maske is listed as 6'3 but we know boxrec measurements are BS Vitali is 6'6 or 6'7 https://media.gettyimages.com/photo...draising-gala-picture-id171016176?s=2048x2048