I used to have one too, and had same issue with mount, never happy. Choice is to put a good rear peep sight on it, or go with a forward mounting rail system that replaces the handguard.
Ruger is now offering these on Shop Ruger, and I've ordered one for a folding stock Mini-14 directly from the manufacturer.
http://shopruger.com/Mini-14-Scope-Mount/productinfo/18081/
http://www.amegaranges.com/
http://ultimak.com/
Saw a photo of a Mini with the Ultimak mount assembled to it on this site and was impressed, however, Amega makes one for the side swivel folding stock.
One warning, is that without the buffer system in the older pre-Ranch Mini's they have been known to "eat" scopes.
The folder I've got is a Ranch version and going to mount a Eotech on it eventuallly.