Actually it's not the lift that'll kill the bottom end so much as the duration. That Lunati should have good bottom end since the duration is only 226/234 at .050. Your only problem with going with a much bigger cam is the power brakes. I had a 274XE in my 360 and it only pulled 10 inches of vacuum. Luckily I don't have PB cause that's not enough to make them work right. I'd guess if you want your PB to work right you better stay with a 268XE or Lunati 60403. But neither of them are actually much bigger than what you have now so you may not notice a big difference.