Time has turned sixpacks and maxwedge crossrams into expensive eyewash. The crossram is over sixty years old, and the Sixpack is more than fifty five.
They both can still work very well, but spending the money for either and expecting a big performance boost is foolish. If you're willing to spend the money for the look, go ahead, but don't expect to be any faster than modern manifolds and carb setups.
I took a modified tm7 and 850 dp (to maxwedge ports) off my roller motor max head 440, and put a crossram and two 750 competition afb's on. After final tuning, the crossram picked up.........nothing.