Sounds good Hubie - but be careful not to set it too high! It's tempting . . .
The battery's state of charge will in considerable measure determine the ammeter reading, as the regulator will want to get the system voltage up to the prescribed level and hold it there. If it's less than fully charged, the dynamo will be briefly asked to work hard to get the battery up to spec. Ideally, you only want a small steady charge with a fully charged battery regardless of whether the lights are on or not, when rolling along. What you don't want to do is overfeed the dynamo's field coil to obtain a larger than needed output, as that's how armatures get fried. Changing the regulator setting changes the amount of time the contacts are open, and therefore the amount of time the armature's output - D - is being fed directly back into the field coil - F (as well as to the ammeter/battery etc of course). All the regulator does is interrupt the connection between the dynamo's output (D) and the field input (F). At rest the two are connected, in fact they are always connected except when the regulator is in regulating mode with the contacts trembling. The shorter the time the points are open as opposed to closed, the more output from D is fed into F and vice versa. While the field coil is quite tough, the armature is more vulnerable.
You've got a safe 60Watts continous power at 6v, your electrical loads with tail, head and speedo are going to require a lot of that (I forget what bulbs you've got but let's say that's about 42watts). 42 Watts at 6 volts requires the dynamo to deliver 7 amps; the battery will also need its usual trickle to keep things in shape, so that's 8-ish amps say, compared to a 10 amp maximum load (which is fine). If you find that with a fully charged battery, all loads on and at road-going speeds, you're getting a charge of more than an amp or two shown on the ammeter, then I'd back the reg off a bit to calm the dynamo down. Some Haynes manuals, and also the Lucas Service sheets, contain quite detailed guidance on this stuff. Correct setting is critical to the management of the field. Poor management of the field is the primary reason why dynamos have got such a lousy reputation over the years - and it's usually not the dynamo's fault. It chucks out according to what's chucked in. Too little and the lights start to fade and the battery isn't maintained; too much, and the armature is overworked and the battery may also be overcharged, with consequent water-loss and shortened life.
You'll always get a temporary surge in charging after you've been sitting at a traffic light on tickover for a few minutes or something with the lights all on, that's normal as the battery gets a necessary boost to compensate for the drain while you were sitting there, but the boost should be short term.
