I would strangle someone if they messed with that barn. It's got lovely character. The stalls under my main loft are about 8 feet high. And the side loft won't be much higher - in fact it could be lower and that is the side my husband's 16.2 hand Shire mare has her stall.
I would also try and work with the drains. There has got to be some way to keep them and use them without having to keep stepping over them. Because if they were build in, they are going to be functional and easily cleaned out. Priceless if you ask me.
I can't tell from the angle of the pictures, but the metal posts look like they may be good markers for the stall wall dividers. I think my old barns wooden support beams are about 12 feet apart. The divider walls are about 9 or 9.5 feet long. There is no way I am going to rip out my loft to raise it up a couple of feet. Gotta work with what you got sometimes. I think if I had pulled up and seen a barn like that on my place, the house and everything else would never have been looked at - SOLD!