Which resistors to use for KT88 output tubes

Another point on your bias resistors: Find 1% tolerance pieces(but, you probably already know that).

Metal films like Vishay and Caddock, are excellent, but good wirewounds have actually proven to be quieter. ( http://www.aikenamps.com/ResistorNoise.htm ) It can't hurt to have stable/quiet resistors, in every section of your circuit.

Again, the Vishays and Caddocks I was referring to, are both Metal Films. Read the paper again, in that light. Yes, this has also been my experience.

Mills makes some nice, non-inductive wirewounds and what I would probably choose for the screen grid: (http://www.hndme.com/productcart/pc/viewCategories.asp?idCategory=54) I wouldn't use carbon comps anywhere in an amp, that I didn't want to exhibit colorations/noise(ie: audio reproduction). I've also purchased a number of Metal Films here(see pages 10-12): (http://www.percyaudio.com/Catalog.pdf) Michael used to have a $50 minimum. Don't know if that still applies, but- if you're building an amp; you should surely be able to find enough goodies, in his catalog, to make that up. He will also match components(ie: for channel balance), to <1%, for a small fee.

Let us know how your amp project turns out.