An extended magazine release for the Ruger Mark II will work just fine in the Ruger Mark I and Standard pistols, no "modification" necessary, and I do recommend that one of those be used instead of the factory latch/release when using the newer style Mark II type magazines.
The original latch/release works just dandy with the solid, non-removable base plate magazines, but the smaller radius on the working end of those releases gets hung up in the gap between the base and magazine body:
I don't believe Volquartsen offers extended magazine releases any longer for the Ruger Mark II pistols as I can recall seeing those in the "clearance" section of their web-site.
Here, I only use and sell the
Ranch Products releases in both black and stainless steel.