A big block radiator would have the lower outlet on the Driver side, this one is passenger, so I think you have a 1968 small block SJ radiator.
The 1967 Big Block used a 22" radiator, not the 24" like the 1968-1970 used.
With October 1967 date,
I'm thinking it is from a 1968 San Jose, Mustang or Cougar 289(leftovers, not sure if SJ had any 289s left)/302 with extra cooling option or A/C.
The 1968 289/302's with extra cooling would have a 24", but I think only 2 row while the big blocks were 3. (That I'm not positive of, I think the 1969's with 390/428 had a 3 row, not sure if 3 rows started in 1968.)