Not exactly what you're asking for, but I thought these might be interesting.
A while back I converted some Atari ST music to 5B to test it (since they're the same chip, just at a different clock rate). These are rough, but they were an interesting proof of concept. Note that for toki6.nsf the difference in clock speed is too much for the envelope bass to function correctly and sounds terrible. Also puzznic.nsf does not manage to get the whole song in; I cut it to fit without bankswitching.
I hacked a YM player to dump out all the register writes, changing all the frequency register values to ones appropriate for the 5B clock. I feed that into a simple NSF program that just plays back those register writes.
This .ay is 0kb... anyhow, now that I know it's for VT2 I realize I can open it. (I have VT2 but only used it once.)
Anyhow, yeah, the beginning wouldn't convert well at all, there's not much frequency resolution available for the high range of the envelope generator on 5B.
