it looks f*&5$£g gorgeous Funky.
good to hear you finally got to ride it
If the spit back is only on one cylinder then the issue is not a general timing one but an issue with something associated with that particualr cylinder.
ie Float height excess fuel , oil leak, air leak, leaking valves,Pilot circuit, spark etc
I would start by checking and adjusting the valve clearance. Don't forget that you adjust the cylinder thats at TDC on its compression stoke then turn the engine over to TDC before adjusting the other side on its compression stroke
The problem could be with the points and the advance . The cam timing is easy enough to get spot on but its worth rechecking. It is a stock ignition isn't it ?
The long term solution of course is to fit a Boyer Bransden Micro Digital ignition system and then you can forget it. The ignition timing will then always be absolutely spot on
You will need to read your plugs now as they should tell you exactly what is going on in your engine. Clean them thoroughly or better still fit some new plugs. take it for a spin for about 10 miles and pull the plugs. Make sure you keep them seperate left and right so you can compare cylinder differences.