It look like an IH carb (not a Zenith), get a kit from an IH dealer or from Steiner Tractor parts, don't get one from TSC or you will be sorry. It costs a little more but this is one of those things you get what you pay for.
This is a complete kit and includes the idle tube that can be expensive by itself, they have cheaper kits if you don't need the tube.
http://www.steinertractor.com/IHS825...tor-repair-kit
Be careful separating the carb, the idle tube is often broken during this procedure.
You can get a FREE replacement Safety gas cap through the following link
:
http://www.tmtractor.com/new/fl/fuelcap.htm
Nice looking LoBoy!
Good luck,
David