We know that he’s 240 after the S4 augments, up from 196 (gaining around 44 pounds of muscle and cybernetics), and since Vale is 6’09 armored I think we can estimate he’ll be around 6’10 and Locke at 6’11, sound about right?
In or out of the armor?
Locke seems to be as tall as the Chief when they’re shown clashing against each other in the small preview that was being shown in movie theaters. Buck seems to be a bit shorter than Locke.
http://i.imgur.com/2b1iDKE.jpg
So I’d peg Locke at around 7’1 or 7’2 and Buck at around 6’11 or 7’