This lens was re-designed from SUPER ROKKOR 50/1.4 for MINOLTA SKY RF camera, which had never become a commercial product.
They scaled up the original optical design for SLR use, since it needs a longer back focus (register) distance.
This lens has been modified to EF-mount: See > https://pbase.com/kkawakami/lens_mods_minolta_mc_lenses_to_ef