Lifters and Cam removal?

My dad and i are going to do a cam swap on the Z. He has built many engines and overhauled a crap load of stuff. Anyway, he has some questions, like, do we need to change the lifters, and do the heads have to come off to change them? and also, can the pushrods be changed with the heads in? a general cutaway of an LS1 might be helpful for me to show him so he can see some differences it may have from normal 350's and such.

Thanks Guys

no need to remove lifters or heads,
http://www.ls1howto.com/index.php?article=23
this will help you out

Or get a Haynes manual.

use ls1howto...much better than any manual