Tony,
That looks like a BSA 300 watt charging set. Unless you have disturbed the points mounting plate, the timing should be alright. I do not have any info on these, but used to get a lot in for repair in my past employment. The main troubles we had with them was sticking valves, where they had been stood for a while. The manual, I think, an Clive will confirm, is in EMER Power. A rule of thumb for timing would be points just breaking when piston is 1/16" BTDC. A lot of people do not realise that these sets have form of dynostart, meaning, if there is a battery connected for charging, with a little bit of power in it, by pressing the red button on the panel it will self start, better than snatching away with a frayed old rope! Is the points gap on the data plate attached to flywhhel cover?