Hi Scott, the ZZ cam is a popular swap for people who want a roller but don't want to spend a lot of money. Yes it will work, I think the only thing you have to do is use a Gen VI timing gear but I'd have to confirm that. You also need the "dog bone" keepers for the lifters from the ZZ and the valley plate the holds them. If you're looking for 6500 the ZZ cam won't do that, at least making any power. The power curve on that cam is done by 6000 with a good set of springs.
It would depend on what the original engine configuration was to determine if the old cam would do anything for you. In the ideal world because you have a collection of different parts in mind (no problem with that you just need to match it up) a custom grind would go far to make it all work together. That's spendy but the rewards are great...