Internally Balanced 360 Cast Crank

Well I was speaking in terms of a guy needing to buy a crank. Obviously, if you already own a cast crank, that $300-ish balance job is cheaper than a $750-800 forged crank.

So let's go down the cat crank road for a minute: I have never had a cast crank rotating assembly balanced, but just might soon.

That said, what is the safe RPM for externally balancing of a 360 do y'all think??