Belgian Malinois

I rescued 2 female mal puppies.  they were bred for special forces work in israel when i was with the military there, passed the program tests, but i was allowed to keep them as a personal favor to me from my commander as my dog (their sire) had died in the line of duty. they are 21 weeks old, 30lbs.  They are on the lean side for joint protection.  they are eating a lot. The sire and dam were both on the large side.  the vet maintains that they will get up to 75 lbs once they finish growing and fill out.  Does anyone have an opinion on what their final weight might be given their growth rate (they were 11 lbs at 11 weeks when i brought them home).  It's just a curiosity question for me, but i would be interested to hear anyone's opinion.  guesses are more than welcome, as im sure there are people here with much more experience with malinois puppy development and growth trends than myself.

also, they sleep in the same crate, and refuse to sleep apart. they will bark and bark if they are kept in adjacent crates even.  they even sleep together if napping on the floor, or outside-- its sort of weird but they are independent and very normal (for high drive mals) the rest of the time so i see no reason to break it.  can anyone suggest a crate that might be able to fit 2 fully grown mals? I have a large one right now but they will soon grow out of it.