We have a runner! Head gasket arrived today.
Turning over the engine on the workbench the compression seemed really good, thought it was going to be tough to start without the decompressor but no. A few pulls and it fired up and I think it sounds OK. Ran it for a while at different revs and it seems to do what its supposed to.
Instead of a spark plug I got a sump plug to fill the decompressor hole.
The head gasket I ordered was from
http://www.victaspares.co.uk/Supposed to be a powertorque one and although the cylinder hole was good the bolt spacing was a bit further, presumably aluminium block. Had to carefully widen the bolt holes.
Also crafted an old fashion kill switch to ground the spark plug. Kind that I think are on older Victas - piece of metal bent of the plug. Left the carb kill wiring disconnected for now.
Would post video but will have to edit down to 2MB. Will also put a few pictures up when I get a chance.
Any advice for what I should do with the vacuum tube for the decompressor, should I just seal it up for now?
Now just waiting for the grass to grow so I can try it out.
Thanks for all your help!