Thanks Bob,
I have bought the ebay G200 tank - hopefully it will arrive soon. Should sort me out, so thanks for measurements.

Sounds like you would recommend adapting a briggs muffler rather than visit an auto muffler shop. I will visit my nearest Briggs store and see what comes close in shape. Might get me to a position where I can bolt on a heat shield again rather than a car hot bare metal scenario. My local 'Macs mufflers ' auto store was talking $130 to adapt/weld a car muffler to my manifold which is getting a bit expensive for a 1/2way solution.

Thanks again for your trouble in taking pics.
regards
brian