How hard would it be to swap out oe rocker arm and spring with a upgraded set, what are the challenges

 

It will be easy, the toughest part will be the springs, which are a snap with the right spring compressor and making sure you keep the valves from dropping (compressed air in the cylinder or put the cylinder being swapped at TDC) personally though, I would spend the money for the rockers on a new cam and springs.

 

how do you put air in the air in the cylinder? Just a question

 

they sell a line that plugs into your air compressor and blast air in there. i think i got mine from texas speed, along with my spring compressor. id order a few extra valve seals, and keepers for the valve springs.

 

Biggest challenge is not dropping anything inside the head (small sockets, keepers, or anything else) The dual spring compressor sold for LS engines is BS, it does not hold the springs centered and its a pain in the *** to get the keepers back in. Single spring compressor from any auto parts store works best.

 

Which one are you referring to? I've used several different ones and they work just fine. There's quite a few on the market these days.
The single spring comp from Advance or Auto Zone don't work for **** on a dual spring.