The current crop of 45mm USD forks are very similar to an early showa example.The reason you have a lot of play in the bushings as you have already pointed out is to try and overcome some of the binding that is prevelant in this model. The bushing lan on the chrome tube has not been relieved to allow the bush to flex as it passes through the triple clamp area. If you can take the chrome tubes to a competent machinist and have the bushing area machined the same as a modern KYB you will have a remarkable improvement in the responsiveness and feel of the fork. If you have explored the valving on these forks you will notice that the compression valve is extremely soft while the midvalve is really firm. It would appear that the midvalve provides a great deal of the damping within the fork. This can be a compromised situation. With such a soft comp valve and such a firm midvalve I would be concerned at the possibility of cavitaion within the cartridge. The rebound damping on these forks can also be improved. If you wish to record the valving and present it I would be happy to make some recommendations for you. Also I find the Marzzochi forks work best with a relatively low oil height 130 - 135mm 5wt.
Regards
Terry Hay
Regards
Terry Hay