Zenith makes an excellent carb; however one was never original on your truck. To determine if the carb is applicable for the 235, we would need to know the number on the Zenith tag.

As a general rule, too small a carb will run too rich up to a point, where it just won't run; too large a carb will run lean (need to add choke).

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop