to me it looks earlier than a 60's frame, we had an original Rensch tandem in the shop awhile ago that had a fancier version of the initial R on the head tube along with the playing card emblems on the seat tube if my memory serves me correct.......looks also to have a headclip rather than a headset and a b/bracket oil port which would place it 1950's or possibly earlier, very nice and definitely worth restoring!