I think for the first time, the playfield needs stripped. Then it's all a matter of what it looks like. I'm a Novus 2 fan, we use it for everything, playfield/plastics/targets etc. All the metal parts get polished with a bench grinder/buffer and rouge. Small parts like screws and such go into a vibration tumbler.
If the playfield isn't up to par, we use a buffer (like the one in the kit, but we get them on ebay.) with novus 2, followed by hand coats of Mothers or Mcguires or whatever carnuba wax (solid wax in the can) for at least 2 coats, sometimes 3. And always brand new balls, new shooter springs and tips, and all new rings.
And when it all goes back together it's something to be proud of. I guess you can cut corners, but if it's your machine don't you want it perfect?