As I don't know how to add pictures here, I'll try to explain. The wedge is a bit wider than the footprint of the fork crown shape where it contacts the spring and has notches for the bolts in order not to shift or slide off. Basicly, the wedge needs to be the same shape as the underside of the crown where it supports the spring, in order not to load the crown or bolts in some dangerous way. The wedge angle depends on how much you need to alter the spring aspect.

Basicly when the bike is on the ground, on its wheels with no load, the rockers shold assume roughly the same angle as the lower fender stay or a bit more acute angle. The wheelaxle nut should be partly or fully visible under the fender stay. Certainly not a shallower angle than that or the suspension will be hash, rough and unresponsive on the road.

But first you need to carefully investigate the reason why you need to change the geometry of the suspension. Very small tweaks of the fork shape or spring connecting links does a big difference down at the rockers!

Is the fork bent? A small head on accident can bend the fork backwards. Small differences are very hard to see with the naked eye. You need measurements in 2 or 3 directions with the fork preferably in a jig or on a table.

There are differences in spring connecting links. Are they the right ones for the fork?  If so, do they have the right shape? That too is very hard to see with the naked eye. It is crucial that they both are exactly the same length and square to the spring.

Is the spring tired or bent or it's eye bushing worn in some way? In some cases spring leaves can be hammered back cold, but it comes with a slight risk. New spring packs is available, and in fact a complete fork as well.

Geir, the length of the rocker hangers was changed a couple of times during 101 production. Also, 101s often have older ones fitted. The ideal angle for the rockers to sit at is approx 35-45 degrees to the road to absorb shocks and transfer forces vertically ( if the rocker angle is level to the road, the tendency is for shocks to be transfered thro the head stock, and not via the springing action of the leafspring) We have found factory made shims under three forks here in the last few years, and machined up a small batch. However, the two bikes we tried them on did not need them, as they increase the spring tension and caused the front end to bounce excessively when sharp bumps or potholes were hit, altho they did smooth the ride out to a certain extent.

The wedge shaped shim sits between the fork casting and the leaf spring, between the bolts, lifting the front of the leafspring , and hence increasing the angle of the rockers.

The frame and fork geometry is  good as standard, the hangers from the leaf spring to the rockers are often bent and affect the posiion of the rockers, you need to check that the rockers sit evenly, and in identical positions. I have seen mismatched pairs on several occasions that cause the front wheel to sit out of true.