Okay so...

I go measure the chain line - 45 - just as it was before...

I take out the shifter cable and run a new one, reposition the derailleur just a hair under where it was before, and slightly towards the chainrings in front...

Tighten it up and reattach the cable...

And it works - With the ten speed chain.

All three rings, no rubbing except towards the extremes, which I never get close to anyway.

Wonders never cease.

Thanks.