It would be sweet if there was a long rod available.  Like about 3mm longer, which would bump up the CR and also provide more mechanical advantage.  But I suspect then you would need to rebalance, and of course someone would have to break down the crank, install the rod, true it back up, etc.  It would be a mighty fine performance booster.

These guys might be a possible source.

http://crankworks.com/index.php/crank-services