Nowadays, all one has to do for a pair of nice flowing, cnc ported 906 heads is make a call to Dave at KG engines in Kansas Ohio.
He’ll fix you right up for a very reasonable price.
My days of high effort ported factory iron are over!!
pfhhhhtttttt.......specially with cast iron! It's so costly in tools it's pathetic! Take that money and get some aluminum heads and have them worked. You'll likely come out cheaper.
