'324 is just a '1284 with less memory.
With not too much fuss should be able to mimic maniacbug's '1284 files with the '164/'324'/'644 (and A, P etc) specifics.
- add a '324 section to avrdude.conf if not there already with signature bytes, memory size changes
- add a '324 section to boards.txt with avrdude.conf name call out, memory size change
- reference the '1284 bootloader and whatever pinout_h file you want to use