If the gun runs, and the height works for you, I'd say leave it alone. It's really just an aesthetic thing at this point. If you want to run irons you have a problem, but you are good to go with the scope. I'd go with one of the smooth free floats, like the JP or similar. You can add a rail if you need one or just leave it be. I'm sure one of the Phoenicians will help you out when the parts come in.
Judging by the pic, if you swapped to a low upper, you might need new rings as well.