I'm another sucker. I ordered a replacement chain from a Honda dealer for my 550 ages ago. I guess he wasn't aware & I certainly wasn't aware at the time of this clearance problem. They supplied me an o-ring chain.
Since seeing a few posts here in the forums about the clearance issue, I thought I'd better check. Sure enough, I have a decent gouge in my case, not enough to cause a leak yet, but oh so close I reckon.
Yet another example of how valuable this site is for providing excellent information.
Pic below is of the chain in question. The plates have had a rub, but it's the pins that have inflicted the damage.
I've found a Tsubaki outlet not far from home, they have the QR Pro Gold in stock. I kinda liked the oring chain with its brassy look, so I'm hooked on the gold finish of the Tsubaki chain.
Thanks everyone for the tip off.