Thanks icko,
The bottle is the Flash Lube Valve saver kit, automatically feeds through inlet in the carby spacer by vacuum. Saves putting it in the tank and cheaper. I actually have Unleaded head, so probably not necessary but doesn't do any harm. A little bit of extra protection.
Checked Dwell and Timing and all seems okay, Dwell was around 40deg so adjusted to 48 deg. It helped, but might be a dodgy plug causing rough running issues.