I know you got it by now, but...
All you guys should get a set of metric O rings. the set does not include O rings as big as the fuel tank ring but covers many other possible neads for O rings.
Check out:
http://www.mfpseals.com/
you can buy a kit with graduated sizes of Metric o rings for about $35.00.. this kit is not on the web site, so Call them and you and ask about the Metric O ring kit. this will save you a lot of grief and $$$$.
aaronl