[Arran]

There was some debate about whether a brand Z 1000Z could receive up to frequencies as high as 64 MC but the general opinion was that it was highly unlikely whether they could given the front end design. Apparently the 1000Z uses a 6A7 convertor tube and pentagrid convertors tend to produce a lot of noise at higher frequencies. This is why most higher end shortwave sets from the 1930s and 40s tended to use separate mixer and oscillator tubes or duel section convertor tubes like a 6J8, 6K8, etc.
Of the two makes I would put my bets on a high end RCA being able to receive up to 50 MC, or a Philco 37-665 up to 42 MC over a brand Z set just because of the layout of the band switch and the related coils. Of course tuning up to 60 MC in the mid 1930s would be something that a 1000Z or other radio would be something that likely couldn't be confirmed or denied at the time since there likely wasn't much going on at the frequency at the time.
Regards
Arran