It sounds like you are interested in merging harmonized CPS data from IPUMS with the NBER merged outgoing rotation group (MORG) files. Note that IPUMS CPS offers the outgoing rotation group data together with each ASEC (1990-onwards) and Basic Monthly Survey (1983-onwards) sample. The Outgoing Rotation Groups (ORG) variable selection page displays the harmonized ORG variables that IPUMS offers, including the variable UNION. An extract with both ASEC and ORG variables will have a single observation per person, with responses from each component already merged together onto the same person-record.
The NBER MORG file will code occupation and industry based on the Census Bureau classification system that was used contemporaneously (see the MORG documentation for reference); the corollary to these unharmonized values are available in IPUMS CPS as OCC, IND, OCCLY, and INDLY. I am linking to a blog post and forum discussion that include information on merging IPUMS and NBER versions of the CPS data.