RE: FT-240 Cam/Crankshaft Timing
The timing marks are usually set so that they are in a straight line between the centers of the crankshaft and camshaft. They would be adjacent to each other in the center.
To de-gum an engine, you can soak it in glow fuel. The fuel will dissolve old deposits. You can also disassemble the engine and use "four-ought" (0000) steel wool to clean the parts, but you must be absolutely sure to get all shreds of the steel wool out of the engine before you reassemble it.
Any good cleaning solvent, such as varsol will also do the job. Just keep it away from the rubber o-rings in the carb and on the pushrod covers.