73 GTV resto - rebuild or replace brake and clutch MC?

Hi All

I'm maybe halfway thru restoring my 73 GTV which was bought as a project. I've never driven it and am unsure of the condition of the entire braking system. I'm wondering what is typical to find with the master cylinders? Mine is an ATE. It looks like its in decent shape, should I simply get a rebuild kit? I was surprised to see that new MCs are available for about $75 and was thinking of just replacing it outright for ease and safety....

Do the brake proportioning valves need any service?

I did have to fiddle with the clutch mc to get it to disengage the clutch and I know its leaking. Are these typically rebuildable when leaking or do you often find they need replacement?

Thanks all