Do the bars your talking about look like this one?
This is a 36" .404 but you noticed I never said how it works for sure with this setup, because frankly this saw has not been started since I restored it.
I think it will do ok with it and I intend to fire it up someday when I get time and find out. Might have to wait till I retire though.
What are the NOS 28" bars you speak of? Are they the same style as this? If you found a stash of them and the price is right I might be in the market for one or two. After you get yours of course. I could put one on this saw and move this 36" .404 on to my PP655.