So why piss away $300.00 for an internal balance when you don't need it? If you want it internal, buy a forged crank.
BTW, I don't know who is doing your machine work, but they are either double damn good, or he works way too cheap. $300.00 wouldn't get you a balance job with Mallory. It would start at double that, and go up from there and would depend on how long it took, with another $50.00 just because it's such a pain in the *** to do it.