Hi cobbadog, It is Swanson Gaskets in Sydney, I saw their advert in the Tomm magazine and phoned them yesterday, the gentleman said it will cost about $100 for a 4 cylinder head gasket, I thought that was very reasonable for a one off job so have sent up the old one as a template. You can buy new valve grind kits for this tractor in the USA for about $100 Australian dollars, but you still have another $75 or $80 in postage costs, plus the risk of it being bent in half when it arrives.
regards
mike