Oil pressure problem

Not unusual to see your figures which is why Norton deleted the oil pressure gauge..
If your engine is not wet sumping quickly, I wouldn't be too concerned. 
You could check the sealing washer fitted on the pump to seal the oil flow to the timing chest for peace of mind.
Further inspection of the oil pump for wear will give greater confidence as well.

Not unusual , consider changing to 20/50 oil ,easier on the engine on start up . You could strip and clean the PRV valve . 

Ian and Robert are correct. Same story with my model 7 which I've been riding for nearly 3
decades. Enjoy.

Many years ago, when studying for A-level Applied Mathematics, I did a back-of-envelope estimate of the pressure generated at peak revs by rotational forces on the oil in the big-end cavity of the crankshaft.

If memory serves, the answer was around 50 psi. Conclusion: when you have the motor well wound-up the main requirement of the oil pump is that it pushes the oil along fast enough to keep up with what is squirted out under the above-mentioned forces.

When the twins first came out they attracted a lot of comment about the oil pressure dropping to zero when hot. Norton set up a rig with an engine with no oil pump but only a gravity feed and ran it at full revs in front of some motorcyling press. The emphasis was that the centrifugral force of the rotating flywheel was sufficient to draw oil through the engine without the need for the pump.
Then they just deleted the oil pressure gauge to stop the complaints.     

 That leaves a question,  So where did every bit of  the oil pressure go ?  Centrifugal force pulled most of  the oil out faster than the pump could supply ?, probably,   but also  could it be that crank flexure at high revs  allowed a bit more leakage between the bolted up crank faces ,even more so when oil was hot and thin ?,  Anything we can do about that ? . Lightly grind the faces together  with valve paste for a better fit ?  Its well known that the drive side was not as well lubricated and was prone to seize on that side . 

My Dommie has a thin paper gasket.  The conical seal tends to be squeezed so hard that it is in danger of its edges coming away.  Are the ones we buy now thicker, to suit  later thicker Commando gasket?  Take care it's not too distorted if you add a washer to Dommie.
The lip seal in the cover is a possible issue.  The recess in my cover is just a little too shallow to get the retaining circlip back, and I end up removing some rubber from the back face of the seal.

Please see your workshop manual.
When correct conical seal, washer(s) if required and gasket are in place , the timing cover should be forced away from the gasket face of the crankcase.
You should be able to get a .010" feeler gauge in.
​​​​in.Beware of timing covers which have been surface ground and thick commando type gaskets.
Hope that helps