The only way to get more lift is to increase your rocker arm ratio to 1.7. That will increase the lift at the valve. You won't get any change in duration or LSA. Doing the math, there isn't a ratio that is available that comes close to the XP. The XP also has a much different lift profile than a VS. The VS has 0.005" more intake lift than exhaust lift where the XP has 0.016" more exhaust lift than intake lift. There's no way to get similar numbers by changing the rockers.