I don't think you'd ever find an authoritative source for the "right" chords, and even if you did, no one else would be using the same source, so what would be the point?

I agree it can sound a bit of a mess when there are too many chordal instruments, but if you're not playing in a performance or a band, maybe it's not such a big deal. I try (on melodeon) to listen to other instruments and follow their chords when I can - sometimes - but other times I might just stick to what I like and ignore them. For instance, in Staten Island I'd prefer to play D / G / D / A at the start of the B-part. If I feel it's sounding too much of a mess, I might just leave out certain basses if I know mine would clash with some fancy riff.

Basically, if there are melodeons, they have a restricted range of chords and you may just have to follow them (and some melodeon basses are difficult to ignore, believe me, they're not all wheezy and vague). This won't be too taxing but may get a bit boring for a good guitarist. On the other hand if you get a piano accordion, they have vast numbers of chords and may use them just because they can. This fits with what Vic is saying up thataway.

So forget about "right" chords - I think all you can do is listen and work it out as you go.

Marje