I have one of those filters too. I also have an
sales brochure from 1965, it shows the typical
filter, the one with the long air spiggot like on
my 62 Invader and my 63 Nova (I used to have).

Is the oil bath filter correct? Luckily my mess
is still good. I have an owners glovebox manual
coming, maybe it will tell me about how often
you need to add as I have never dealt with this before
either. My manual otta be here this week or next.
I'll post any info