The 1964 300Ks with ram induction are supposed to use a different air cleaner than the earlier cars. This is done to give more clearance from the passenger side air cleaner from the air conditioner box on the firewall. The lids are the sames but the bases are where the difference is. See the excellent page on the club website for the research done on this.
The basic difference is that the indexing piece on the bottom of the base is placed in a slightly different position in relation to the carburetor. See the attached illustration. See the relationship of the indexer to the bottom of the stud.
I've now seen two sets of air cleaners from 1964 cars where one base is the new one and the other is the old one. If you have a ram K, can you look at the bottom of the air cleaners and reply back to tell us which bases you have.
Thanks, Nick