There was a thread on this subject a few months ago and the fuel resistant materiel that was talked about is "Nitrophyl" available from "Restoration Supply 1-800-306-7008". If I remember correctly, you work it like wood and make your own float. There were other suggestions so maybe you can search member (Steve A) and find the whole thread. Hope it helps you.
Grant.
I put in a black float from Cat over 20 years ago and it is still 100%. Maybe find one that is better quality?
I wonder if that is still an available part from CAT? Anyone happen to have a current part number?
Thanks,
Jordan
Edit: Quick ACMOC search I found some helpful links/info;
http://www.acmoc.org/bb/showthread.php?16591-Where-can-one-purchase-a-zenith-carb-kit
http://www.russellsnewoldparts.com/floats.html
http://www.thecarburetorshop.com/TrackitsC.htm#TracCate
If the float is # 9b4922 is available $12.00.
I put the float from Cat in about 4 years ago and it's good so far.