Never seen one that used a clip. I know the magazines are kinda expensive for the originals. How do you know it's not a MKI? It's pretty simple to tell the difference between a Standard and a MKI, right?
From Google....and I've read it and heard from people I trust:
All MKI's were marked RUGER .22 CAL LONG RIFLE AUTOMATIC PISTOL MARK I. Earlier ones had Ruger Pistol which was changed to RUGER STANDARD AUTOMATIC PISTOL. 1958+ Standards were marked RUGER .22 CAL LONG RIFLE AUTOMATIC PISTOL.
To answer the question, the value is likely between $150 and $1500. Since we don't know what model it is, its condition, or what it looks like....tough to say. Is it a perfect 1950's model with a vintage maker's marked holster and comes complete with a serialed box and all its internals? Or is it a nice shooter with no extras from 1980?
Pass the gravy.