Roller cam

Thinking of going roller cam in my drag car this winter. I'm looking at 2 cams. One is 263at .050int. and 269 at .050 ex. Lift is .675 in. and .650 ex. Other is 270 at .050in. and 275 at .050 ex. Lift is .670 in. and .635 ex. My question is what is the purpose of less exhaust lift. Most cams have more on the exhaust.
More info needed about eng
Car spec would be nice also