Your options for Academy 1.33 are 4-perf super 35mm film, Arri Alexa (with the 4:3 licence), Arri D21, Arri Alexa 65, and Panavision DXL. The full-frame DSLRs would give you the coverage, but no way to mask it while shooting.
Barring those options, you're looking at cropping in on all the other S35mm cameras for a 4:3 ratio.
If those options are out of your budget, I know some anamorphic-lovers who like the GH4/GH5 and the 5D3+RAW/5D3+ML, maybe it's worth checking if those do 4:3. And in any case, cropping in post does work pretty well!!
The GH5 is supposed to be getting a 6K/24p 4:3 "Anamorphic Video Mode" firmware update that utilizes it's entire sensor. Believe it was initially scheduled to arrive by the end of summer.