Finally got the Octura carb & 'go-louder' exhaust fitted to my boat engine, the engine still needs rebuilding at some point on the future, will have to make another tool to get the cylinder off.
Hopefully I'll find a more original cylinder in the future, this one has been bodged by a previous owner, they didn't even bother to remove the cylinder as there is lots of solder splattered on the inside of the starter.
David