Kramer-
I think the air cleaners are something you can actually live without. I drove race cars witha Buick V6 with a Kinsler FI system and most of the time we never used any kind of air filter. I wouldn't recommend this since it led to a stuck throttle (debris caught in the butterfly) once during testing that was not pleasant. We went to a fine mesh screen over the stacks and no problems. Granted, they were freshening the motors every 1000 miles, but I talked to the engine builder about this (Ohio George Montgomery) and he said there were no issues with "dirty" air, other than lightly lubricating the butterfly linkage. If you change the
oil regularly, the dust in the air that is in the combustion chamber is mostly removed. He had motors with 50,000 race miles on them with no cylinder wall issues which is what I was inquiring about. When we raced on street circuits, there was tons of crap going into the motors, especially on the first morning of practice (the Miami race was really bad).
If you look inside current throttle body assemblies on "normal" cars, you will see this fine mesh screen on many of them. How you would adopt this to the TWM system is another matter and might take some fabrication.
I know this isn't really an answer, but just thought I'd share it with you. Your motor is one of the best looking I have ever seen, by the way.