I want to put a nice sized cam in my 93 4.3, what all needs to be changed or replaced?

 

depends on lift. anything over .500 lift the vavle guides need to be machined. i had a '98 zr2 s10 that i stuck a 266HR comp cam in... i also ported the heads and intake manifold, had a custom tune (had to do it becuase of the cam) and had to have the vavle guides machined... that truck would hual ***!

 

yeah anything worth doing is going to require head work .....valve guides need to be clearanced and stiffer springs for the extra lift. I put a smaall cam in 2000 silverado 4.3 and it made a difference, not a earth moving difference but a difference nonetheless.

 

I don't need a huge difference right now just a little extra HP and thump while working on looks

 

It doesnt need head machining unless its an older TBI headed motor or using older springs. There are new valve springs out now that dont require machining.
So in your case, Id call comp or other companies and inquire about your heads and if their springs will work or if your can use some Ls6 springs.