I dont know about getting an originall air filter body for that one, is the old one actually cracked, or just sun-damaged, becase I know a trick for restoring it if it is just sun damaged, and looking at the picture, it seems a good candidate.
as to what is inside it, I'm having trouble working out exactly which length that is, no chance it still has remails of the last filter in it, if not, what is the lenght of the body, from bottom to top, with the base cap removed?
If you do have to replace the body, the closest match in the store would be
THIS and
THIS is the closes snorkel i can find, it may need to be trimmed to lenght at the top.
I cant find a carby bowl gasket in the shop, but bruce might be able to help you out, its the same one as for the 3l and 3f.
Let us know how you go inside the carby, anything you need, and cant get from the store or bruce, i should be able to track down and post, carby parts are easy for that.