360 balance question

But the mallory metal that needs to be added to the crank is quite expensive plus the side drilling of the crank to install it adds more cost. You take a balance job that would normally cost $200 and turn it into a $500 job for absolutely no benefit if you aren't turning in excess of 6000 rpm on a regular basis.

The reason the 360 (and cast crank 340's) are externally balanced is because the cast iron in a cast crank is not as dense so the rotating assembly can't be balanced with in the size constraints without adding extra metal. For a street going motor it only made sense to go external balance verse the cost of adding mallory metal to the crank.