750 cubes = BIG $$$ Tall deck block, raised cam tunnel, belt drive etc.
600 cubes will still give you that big cube rumble for LOTS less money. Using an A460 block and a Scat 4.5" crank, you can get in the 600s without going for the radical custom parts.
BTW, any little old small block with the right blower can keep up with a superbike in a straight line
