I got this motor out and was wondering how hard it would be to change the valve seals?

 

And if I do the seals should I replace the springs and the valves too?

 

With the motor out of the truck, it's cake. Just time consuming. Just inspect things while you are in there, if something looks questionable, replace it.

Have to pull heads to change valves, and, if you go that far, might just as well simply buy new, better heads.... would cost a bit more, but, would solve some of the issues with the stockers.

 

i'd replace valve seals, freeze plugs, rear main seal, oil pump,front seal, timing chain, water pump, fix plenum whether they need it or not.
i would not replace springs or valves unless there was a problem.

it also depends some on where you're going, what prompted the pull, and budget. if the heads are stock and you plan to keep the truck and you can afford another $500, then consider replacing the heads

 

And at least plasti-gauge your main and rod bearings to see where you stand.