You should change the stem seals but unless you're gouing for big power i would leave everything else to do with the valves. You should be changing everything on the engine if you're going forged really, like every gasket and seal and all bearings. Not to mention getting the bores honed, block decked and head skimmed (or at least get a machine shop to check them). New oil and water pump, timing kit etc. Most of all i'd get the crank polished, and reground if needed. No point in cutting corners on a forged build.