I'm positive it could be altered many ways, and I know I've seen posts on here from guys who did. I think the most common alterations are shortening it, and cutting out a piece along the front of the neck hole on the chest and sewing the edges back together so that it lies flat without the 'bubble' a lot of people get with the underworks binders. I shortened my double front underworks binder just by reinforcing the stitching on the inside of the two layers and then taking pinking shears to it, although it would be better to serge the edges or do a tight zig-zag stitch on them. I don't wear that one anymore because it's too large now, but it held up fine with many washings that way.
As for changing the armhole depth and shoulder strap width, I would think that would depend on your body and binding needs. In my case, I'm mostly only binding extra skin at this point due to weight loss and breast fat loss from T, so if I were to have the armholes come much lower, since I push the moobs 'up and out' to achieve a flat chest, they'd be falling out the armholes, ha. It's different for everyone though.
