8K? 60fps? How are you going to render out a file that big? Even working with 4k is a pain in the ass. There is no way you could get a file that large to be Blu-Ray compliant.
And 6 hours? There is at most maybe 13-14 minutes if you really try to squeeze out everything. 4 hours is a big number. Jake Lloyd alleges there is a 6 hour cut. But there is no way in hell that they got to that long based on the scripts I’ve read and the deleted scenes I’ve heard of. At most any sort of rough cut would of been half that.
Good luck with this project though. I do intent to do an Expanded Edition of my own at some point, so this could be interesting.