Air Filter Questions for 1983 VT750c

OK So I Have a 1983 vt750 (with an 85 700 engine). I just finished rebuilding the thing. I knew nothing about bikes before I took on this project so some things I'm starting to notice are weird. I just figured out that the filter basket my bike came with is missing a piece. It has the larger part, but not the smaller part that fits inside. I would have never noticed this if i had not had to rebuild the bike. What my question is, is If once i order that piece, is there another filter part that needs to go inside? I have seen round K&N filters on the internet. I'm not sure if something like that is supposed to go on the inside. I have heard a lot of talk about clip on filters, But I really don't want to tear the bike back down after just finishing putting it back together. I'm starting to think the problems i had with my old engine might have had something to do with this. The bike also has had the pipes cut where a muffler would be (wtf), and i was wondering about the kind of exhausts you see that are on the right side as opposed to both sides. Please let me know if anything I'm talking about makes sense.