Yes...although the idea behind flux core wire is to operate without the added shielding gas, the use of the gas makes a weld that looks like it was poured in with a gravy ladle. I think you would have to buy a full spool, and I don't know if the little 180 will hold this, so the idea might be bogus.
I just built some rear spring hangers for my sons Toyota this weekend, and used this process. I have used the wire quite a bit so I knew what I was going to get, but when my son saw the finished product, he was grinning from ear to ear.
Hunt up a friend who has used this wire, or buzz by your local welding supply house and bend their ear. If you can do it without spending a fortune, it make your frame modifications not only strong, but attractive.
Stuart