Unfortunately, it is not a straightforward process to conduct the process if you’re not familiar with geospatial software. The basic outline is:
- Obtain 51 census block shapefiles from 2000
- Obtain the CD and ZCTA shapefiles
- Merge them into a nationwide file
- Convert the blocks to centroids
- Overlay the centroids on the CD shapefile
- Overlay the centroids on the ZCTA shapefile
- Merge the results of (4) and (5) into a single data file
- Merge the results of (6) with the 2000 census block populations
- Roll up (8) by unique combinations of ZCTA and CD codes
You would also be handling large files because there were ~7 million census blocks in 2000.