There are a couple of different balancings-
You can do internal and external balancing.
Internally, you can balance the rods and pistons, or rods, pistons and crank.
External balancing, as I understand it, is the crank, flywheel and clutch cover, and something you do when you change things- i.e. new crank or flywheel? Have them balanced with the clutch cover.
What my machinist told me was that with a striaght six there's no need to balance the crank but you should do the pistons and rods. If you are using the original flywheel, no need to touch the external stuff. My machinist charged $150 to balance the pistons and rods.
Since you are getting pretty radical with your engine I'd definately get everything balanced, especially if you are planning on spending a lot of time at the higher RPMs
Hopefully someone will shed more light on this!
