Didn't feel like reposting twice soo just copied and pasted my response to a similar thread to here as well:
Vanderlei is a tremendous fighter, that said, he isn't perfect and is just a man. Technically he has some issues but has some severe heart and determination, true warrior!
Could someone of Penn's caliber take Vanderlei, sure anything is possible. If Penn was able to move up steadily in weight combination of lean muscle and body fat, doing so where his body naturally matures with a good regiment of training and eating good. Then possiblities of a great fight could be more than likely secured. Penn has the technical capabilities to win, once the size/strength factor is reconciled. Hope he just doesn't rush to pick fights before he is ready. Would be Penn's technical capabilities/heart vs Silva's aggressiveness/heart least from my point of view.
Guess we will just wait and see what transpires, new things happening every day in the world of MMA!