I think it would work ok, never run 8spd on these mechs, so could honestly not say, I think you may get some 'rub' on the extremes, best thing to do is ask in the appropriate forum.. to make sure ..
IMHO the difference between 8 and 9 speed chains and tolerances is so minimal with both front and rear mechs as to make no difference. It's just a marketting ploy to get us all into an upgrade frenzy. I've been running an eight speed chain with so-called nine speed front and rear mechs for a year with no problem.
We do and Bobo has come in with a 28.6 mech so I wouldn't need a shim. So I'm going to pass on your goodies this time. But thank you for answering all my questions