Any chops I have been involved with were always based on leaving just enough head room to be comfortable while driving. It's all personal choice though.
Oh yeah...that truck is badass man. Forgot to put that in my first post. When I first saw it in the top 5 this morning I thought you were going to do a hardtop convertible but I am glad to see you are just chopping the top. It will be sick when you are done!
3 inches is where its at bro. Keith's looks good at 7 for the look he is going for, but for a super clean, just smooth look, i wouldnt go any more or less.