After the informative post I started over last weekend I’ve now established this set of Galfers I paid good money for from Spain aren’t for my Strada-see key below. So, £15 including post..
The sizes are as follows
The homolgation A/1 etc define the brake dimensions for Standard machines.
Rear drum cast wheel A/3 and K sport or Strada are 180mm
Rear drum cast wheel 250 2C and 250T are 160mm
Rear drum wire wheel A/1 and A/3 Sport 180mm
Rear drum wire wheel A/2 Strada 160mm
Rear drum wire wheel A/3 Strada 180mm
160mm are very common in the market, 180mm less common.
So you will need 180mm shoes for a 1980 A/3 Strada or a 1980 on K strada