I started working on that model and have found a few things that are wrong.
Parts B2 and B3 go together to form part of the fuselage. Unfortunately the resulting diameter is too big to fit the B4/B5 assembly.
What I did is to cut down the middle of one of the segments on B2 and B3 then use one of the half segments as a glue tab. You will also need to modify the nose a little to fit the smaller diameter of the B2/B3 assembly. There are no glue tabs to attach the cockpit to the inside of the fuselage so you need to come up with a way to securely attach the cockpit. You could try edge glueing but that does not seem too secure.
I have only gotten as far as building the fuselage from the nose to the cockpit area and am now slowly putting the cockpit together before attempting to attach it to the fuselage. The work is slow because I do not work on it very often, just a little at a time each day. I am beginning to wonder what other problems are lurking in the shadows with that thing.:facepalm: