I'm willing to bet the airfilter is much like what Tomi has here. Old time filters were wire mesh on the outside with paper filament on the inside of the mesh. A lot of filters today are constructed the same way. One exception, there are housings around them as you see on cars, etc. The Torsk filters look like this but do have a housing with the end cap open about 5 or more inches that you can see the wire meshing and filament filter papers. These hook to the intake tube and finally meet the induction ports.
In the really poorly drawn red circles are the filters for the engines. They are exactly like Tomi's but are connected to a intake pipe as this engine was opposing cylinders and the intake was down the side of the engine were Tomi's is on the top. I would not do a thing with the filter Tomi. I'm guessing it hooked to a pipe off the intake and pulled air from the surrounding cabin.
