William MacDuff is also featured in one of Kenneth MacLeay's famous paintings. You can see a small image of it on the STA site, here:
http://www.tartansauthority-shop.com/acatalog/M29.JPG

Anyone know of a better online image?

Yes, his jacket would be considered too long for wear with a kilt by most standards. I note that in the other figures McLeay painted, their jackets are all cut short.

But a long jacket looks good on MacDuff. Are you going to tell him his coat's too long!? Didn't think so.... :-)