Get the DSA StG58A. You won't regret it.
Find out if it comes stock with metal or plastic handguards. If metal, ask DSA if they'll swap the metal for plastic for a small additional charge.
Likewise the bipod. Maybe they'll remove the std, fixed bipod and install the quick-detach version for a few extra bucks. Wouldn't hurt to ask.
You might also consider asking to have them install their scope mount top cover right off the bat. Get the one with the optional brass-catcher if you can.
I realize this stuff will increase the price somewhat. However, if you ask prior to purchase, they will probably knock off some of the additional $ in return for your removed OEM parts.
Most of the things I've suggested above are modifications most FALers come to do sooner or later. Might as well start out right, and save a little money in the long run.