That does not actually work because 90 munition it simply too much.
221 and 222 can be both build-able and/or the upgrade can cost manpower/fuel.
Then road will be open for the 221 to serve as counter to armored cars/sniper and 222 as soft counter to light tanks.
That's fine, these are just details. I think having the 221 as a sniper counter is better than messing around with the 222 any further.