you can get supercheap/repco to order you in the rectangular air filters for these, they come in two heights, the covers have different clips for the different heights,
i went to the redline webber website and they sent me a free catalog, although that was a few years ago and it took about 3 weeks, i can get you the part numbers for the filters if you want, just go to the parts desk and ask to have a quick look at the redline catalog (they usually haveone, sometimes they look at you a bit funny... I'm pretty sure theres a manual choke kit in there too.
it also has baseline jetting figures for some engines... havent looked at it for k stuff yet...
cheers,
rob
p.s. i MIGHT have an old filter assembly you can have for $10 bucks, i think my parents might have thrown it out though cos i left it in their garage (they threw out my black scorpion bush basher on me... bastards)