CR bump would be minimal and won't gain you much. Maybe 5 HP at best.

As far as the intake mods don't waist your time on a stock 5.3. It will end up costing you power in the end.

 

Im not a fan of the 1.8 rockers. Any increase would be minimal and not worth the money imo. I would just do the cam and springs.

 

My drivers side bolt closest to the firewall was also broken, and flush with the head too. I had just enough room to get a mig torch in there and weld a washer on, and then a bolt to the washer, it wasn't pretty but it stuck well enough to turn it out. It can be done!!

 

Thats what gets the job done. I would try everything before I had to pull the head.