Just to clear some things up, the LS7 lifters that everyone refers to are the same lifters that GM has been putting into their engines since 1996. So be sure you're not paying extra just because they say LS7 on them. In the world of GM, lifters are lifters whether it's for the L32 or the 5.7.
I recently got a set of IS3 heads myself, and I was pretty impressed with them. I did opt to swap the 130lb springs for the 105's just because my cam doesn't have a big lift, it's barely over what the XP is, so I can still use the stock timing chain/damper. I'm still not a big fan of the double rollers out just because of my own personal experience with it.
Don't think that I can say anything else that hasn't been said already.
