I`ve read a lot in nightrider and I have de Kip Woodring book, I know that a complete headjob is more efficient if you do it after a free flow air filter, ignition, cam, etc. but since I have to open the engine to replace the bent valve I want to do as much as I can.
Getting any aftermarket part here in Argentina requires at least 30 day, and I don`t want to be without my bike so much time.

 

Porting the heads requires no extra parts as you are replacing the valve anyway.

 

I was talking about changing the cam and gearing, as bucker18 said.
The head is going to be ported and seals replaced, that why I asked how much is safe to increase de CR with stock parts.