John

If you have an old ignition style feeler gauge set that you don't mind sacrificing they work perfectly.
An old set can fix a number of forends.

Those in the +/- .020 neighborhood will proximate the factory spring.

They're a quarter inch wide by about 2 inches long so width is perfect but you'll need to snip them down to get the correct length.
They already have a hole so you don't even need to drill.