Technical Front brake caliper dust seal removal

[hammer man]

Has anyone rebuilt a brake caliper off a 60S? Caliper is a Bendix non ABS unit.
I have removed the piston and inner seal but can't get the remainder of the dust seal out. There seems to be a retaining ring ( different colour metal ring) that looks like it could be prised out but don't want to apply any levers until sure. Any help would be appreciated. Haynes is not much use in this case.

 

[flisko]

never rebuilt it, i just took a working one off a punto mk2 1.2 8v non abs version as they are same

my journey here

https://www.fiatforum.com/punto/420185-mk2-caliper-fits-mk1.html