If you plan to spend the money, why not just go with an aftermarket performance pistion and rod?
Also, a 2v, 3v, & 4v all use the same block. Lots of guys swap 4v top ends onto the 2v bottom ends. As long as the piston diameter and rod journal are the same from engine to engine then they will work. I can show you a wicked BBM built with BBC internals....