A well designed Lambretta race crankshaft should use big end shims for reliability. This is a 1.0mm big end shim for 22mm crank pins. These could be brass or Silver plated.
The Complete Spanner's Manual: Lambretta Scooters by Martin 'Sticky' Round Third Edition 8100072
The Complete Spanner's Lambretta Kit Book 8100027T
Eibar Lambrettas 1954-1989 by Jaime de Prat Salomone
Lambretta and Vespa Street Racers BOOKAZINE by Stuart Owen