Unfortunately IPUMS-CPS does not have an official IND1950 to SIC or NAICS crosswalk. However, on the IPUMS-USA website there is a crosswalk between the Census Industry codes from 2000 (which correspond to the IND codes from the 1992-2002 CPS samples) and the 2000/1997 NAICS codes. Also, each of the March supplement codebooks lists the census Industry codes corresponding to that particular year, as well as their SIC or NAICS equivalent. You could use these tools to generate your own IND1950 to NAICS crosswalk.
You would need to decide what you wanted your “base” NAICS year to be. Say you choose 2002. You could then take the 2002 IND and IND1950 variables from the 2002 March supplement, select one person from each unique IND code, and then look at what IND1950 codes the IND codes correspond to. Since you can get the crosswalk between IND from 2002 and NAICS from 2002 from the codebook, and you now know the relationship between IND from 2002 and IND1950, you can generate the codebook between IND1950 and NAICS from 2002 and apply that to all of the samples.
I hope this helps.