Several papers (e.g., Autor, Katz, and Kearney 2008, Review of Economics and Statistics) use “family earnings allocation flags” from 1964-1975. The IPUMS variable ftotval does not have any flags.
The CPS did not start consistently coding their allocations until 1976. This is why IPUMS-CPS does not currently offer the income allocation flags for years prior to 1976. There are allocation flags in the raw data which is available through NBER and can be merged onto your IPUMS-CPS extract. See this answer for more details on merging IPUMS-CPS and NBER files.
I hope this helps.