Sorry for being a Dick but If you really want to know the Good the Bad and the Ugly of the LS7
http://forums.corvetteforum.com/c6-z06-discussion-100/ use the link read the Forum do the search on ( I drop and EX. valve threads) there threads on checking valves guilds clearness just a ton of stuff that you can help you make up your own mine if the LS7 is a good or bad . I think it can be a good motor if you take the time to pull the heads and make them right .