.060 undersized wont get you .060 gain, got to take .010 off back side of journal to keep it truly round so .050 is what you get, .025 at tdc, .025 at bdc!! so 3.36 best you can do....DWB
Then theres WELDING up and offset grinding. Not that I'd do it. But I have welded up some forged cranks that were not replacable or out of stock.
Now, the question, do you spend the big bucks doing an offset grind and spend big bucks referb'ing the 318 rods, or buy a set of better and longer rods that do not need referb'ing.
Gaining 4 cubic inches with a MAX offset grind to me is not money well spent.