Texas Speed has a head bolts and gaskets. Get the GM MLS head gaskets (not graphite). The GM gaskets are all one thickness. If you want a thinner gasket, you need to get Cosmetic (but, they don't seal as well as GM).

Since you have a 2004 engine, you have to figure out which bolts to use (they changed mid year in 2004).

 

I did cam and 243's on my 5.3. I am lucky enough to have it on an engine stand, but here is what I used while doing it and everything went smoothly.

For general instructions on the swap I used this how-to:
LS1Howto.com

It's for an F-body, just skip the parts where they take the car apart.

You will need to buy a pushrod length checker tool and this is how you use it
LS1TECH - View Single Post - correct pushrod length


For tightening the rocker arms I used this thread (post 34, should go straight to it).
Corvette Forum - View Single Post - COMP Rocker Trunion Install

It's for an LS1 or LS6 but you can use it on any LS engine with the same firing order.

Edit- I went with GM MLS head gaskets and they were marked 5.7L. Just a slightly bigger bore, but it will not make much of a difference.

 

I have a 2004 with the LM7 5.3L. How do I know if it is a 1 or 3 bolt cam face?