very likely you COULD top the ps off with any of the following:
hyd oil ( aw/iso 32/46 etc ). UTF fluid. REAL power steering fluid / atf type f or dx/merc3, or even 10-30 w oils.
what would most of us use? UTF fluid. the common ones .. even store brands.. most meet the ford spec m2c134d some meet the older a-b-c 134 specs. all them specs postdate that machine by decades so would be fine..