Google "recommended torque 7/16 UNF" - the thread size used on Morgan 5 stud wheels. The studs will be high grade steel and the google results will show a torque setting of circa 65 to 70 ft/lbs.
The torque setting is relative to the diameter of the stud or screw, its material grade and its inherrent stretch.
65 to 70 ft/lbs is the setting that I've always used whether for road use or over 10 years of circuit racing, sprinting and hillclimbing in my Plus Eight.
Personally, I wouldn't use higher torque as this increases the load on the thread; go too far beyond and you will reduce the elasticity of the material, weakening it and risk stripping the threads. Overtightening will also risk splitting the inserts that provide the face on to which the wheel nuts tighten. I have had a few split over the years and once damaged compromise the wheel nut's ability. Always replace damaged ones asap.
As an aside, for those inclined to use stainless fasteners on suspension components, think carefully before you use them. Stainless has a much lower elasticity than steel graded fasteners; it's the elasticity that holds enerything tight. Stainless used in applications subjected to vibration and stress is a less reliable material for holding components together. It's also more inclined to fatigue, fracture and shear.
