I'm going length x width on measurements.
It's going to be an all metal barn. Walls, roof, internal structuring, etc.
It'll most likely be all concrete with matted stall floors.
The barn will be 50'x40' with 12' walls and a 15' peak.
Doors will be sliding "dutch doors" that are 8'x6'.
The whole barn will probably be raised around 6" above groun level.
Overhang will be 12'(doesn't look like that in the picture.)
The stalls will have runs that extend 8' past the over hang and be sloped to allow run off.
Outside doors will be sliding "dutch doors" and will be 8'x4'
Breezeway will be 50'x10'
4 stalls that will either be 12'x12' or 14'x14'
Tack/Feed room that will be 12'x12'
2 storage areas for hay, tractor, atv, etc that are 14'x15' and 26'x15'
Edit- I've left enough room so that I can make it an 8 stall barn but I'm not sure if I could add any kind of overhead storage without having too low of a ceiling.