The ‘suprec’ variable was created by UNICON based on the variable FL_665 from the source CPS microdata. IPUMS CPS is currently planning on integrating this variable but I am not able to say when this would become available at this time.
In the mean time you can merge the variables from the NBER files onto the IPUMS-CPS files using the instructions found here: CPS has data available on multiple job holders. Where is the comparable variable in IPUMS' CPS?
I’m sorry I wasn’t able to provide the data you were looking for at this time. But I will pass on your interest in the variable. There are a number of variables that we would like to add to the IPUMS CPS collection and prioritizing is the most difficult part, so any input on variables you are aware of that would benefit your research is greatly appreciated.