Isn't the stripper clip guide milled straight into the receiver on your SMLE? The guide on my 2A1 was removed when it was bubba'ed into a 'jungle gun' (a scope was mounted over the action).
There is a guy who mills stripper clips into various rifles, but I'm not sure if the guide is milled into an existing receiver, or if it is built up out of welding (or something) and then milled into shape. Give Shawn's Tactical
a call and see if he can do anything for you.