I don't have a Barge, but I'll suggest a few things.
1.) Give the equivalent of long range type 3 transport guns (3k range). Might be useful despite the size of the ship. At least they'd be a good sight better than the current turrets.
2.) Increase purchase price to 900,000,000.
3.) Make it publicly purchaseble.
Otherwise I suggest leaving the rest of the Barge's properties as is.