Sorry, I am just jumping in here totally uninformed but are the MkI springs different from the MkII springs? MkII springs are still commonly available.
An easy way to compare is to check the part numbers on the schematics for the MkI and MkII pistols on the Numrich arms website:
https://www.gunpartscorp.com/gun-manufacturer/ruger/auto-pistols-ruger
Aside from the fact that the MKI used 9 round mags vs. 10 in the MKII and the MkI did not have a slide stop they are essentially the same gun. In fact, MkII mags will fit the MkI with a very simple modification. I found this out when searching for MkI mags.
Although there may be exceptions for some parts, as far as I know Numrich ships to Canada.