Which adapter for SIGMA SA-7?

I own SIGMA SA-7 and some YASHICA lenses: YAHICOR Y503 Telephoto and YASHICA Y504, both seem to be 55mm wide. I would like to use them with my original SIGMA lenses 70-300 and 28-80. I need an adapter, but I do not know what brand and size is exactly. Which adapter do I need?