need pics of 1966 273 4 bbl A-833 clutch z bar
i don't know what your skill level of fab work is like, but this type of repair doesn't require a bunch of finesse. flux core buzz box, a 3" spinning wheel of death and some big hammers backed up by a 12 pack would sort that out.
the other, maybe easier, approach would be to find somebody who's parting a car and see if you can get that portion of the apron to stitch in.
or convert to hydraulic clutch.