Further to R's method, I wrapped my springs in Denso tape first and then used the heat shrink tubing on top of that. So far 11,000 miles and no issues at all.

I too would recommend he method

Location: Oxford

At the risk of being a wet blanket, I know the wrapping of springs is a tradition. If s.as. are very good, low spring friction as with a sealed greased spring, is desirable. However with original Sevens I am not sure that binding was not done more or less dry to increase friction and hence damping.
With Sevens, esp at the rear, need all the damping one can get.
One reservation with Sevens when applied to the rear springs is that any cracks cannot be seen. A failed rear main leaf can be very exciting in a Seven. Most failures are preceded for some time by visible cracks. Decades ago an old time spring maker told me that most of the broken leaf springs were caused by lubrication! On the other hand an oiled spring is less prone to develop corrosion hastened fatigue failure.

Location: Auckland