You have a 4.8 right? Are you staying n/a or do you plan on spray or boost in the future? You are stating yoiu dont want to loose any lowend so I am guessing you are runing a stock converter and plan to keep it. If you are planning on staying n/a with a stock converter, I would suggests something lower in the duration with more lift. If you do go with more duration, add in a few degrees of advance. For a custom grind I think this one would work well in a 4.8: 215/215 .53x/.53x 114 +4 That is close to a grind SmokeUr5.0 has on tech in his 5.3 and it seems to do great in his truck.
As for the difference between the two cams above. Since the second one has a more agressive lobe profile and more lift, it should make more power but since they both have the same duration and lsa, their powerbands should be about the same.