Injection Suction Valves 504 t.i

[Cookiemonster]

Hi all, on my newly acquired '79 504 t.i the O-Rings are stuffed on the injection pump suction valves. Taken them off, but can't work out what size O-Ring is correct for replacing them.
Are they metric or AF?
cheers

 

[BIGRR]

See if you can contact "Steve V6" on this site, he will know.