Roadster Fuel Tank Mount Nut Torque?

Sorry for the deluge of questions. While experience may be the best teacher, it can sometimes be a bit painful. Far better to glean as much hard earned experience on the forum than learning the hard way while I finish assembling my MK II after the gearbox rebuild. I'm not new to motorcycle repair and maintenance (including "Limey bikes") but this is my first attempt with a Norton Commando

Since the front studs are cushioned with rubber and nylock nuts are employed, would it be appropriate to use reduced torque to avoid cracking the base of the tank where the studs screw into it? Perhaps similar to the rubber bobbins on the head steady. (12 ft#)

Yes. For studs and rubber washers, I tighten the until the end of the stud is just through the nyloc.
For AV (bobbin) mounts with nylocs then I just nip them up.

I dont use nyloc nuts on the petrol tank mounts, and prefer to use a plain nut and spring washer. I have had a problem where the nyloc nuts 'grip' the stud of the bobbin, and then unscrew the bobbin from the base of the petrol tank when trying to undo the nut.

A torque figure is relatively meaningless when you are running a nylock nut on a stud compressing rubber of an unknown vintage and hardness pulling on a thin skin tin can.
Just tighten the nuts up enough so you can't move the tank around.
Having the right amount of padding between the tank and frame is also part of the "equation".
Same general approach for the rear tank strap.