Well, my 1952 ORER says the GN USRA originals and clones had the same height to the eaves, running board and top of the brake staff, and the same cuft capacity (3098). The only difference is that I can see from the dimensions is that the clones had an extreme width 2" wider at 10'-1" and the extreme width point occurred at a different height from the rail (12'-6" vs 11'-7" on the originals).
Guess I'll wait on the ends if Andrew is working on them.