Well, i think it would be worth a test to give "overwatch" the 223 instead of "early warning". That would be a nice buff but the radio car need some adjustments too. It was only build in only 1 game (Theodosios). I think it should come out earlier to make a difference in combat. My suggestion would be to make it a CP1 /CP2 call-in. The upgrade could be more expensive then. And it should definitely give your teammates resources too.
If you wanna make the 223 a unique unit for a certain commander, then we could talk about moving the 223 to "Overwatch" (replaces Early warning) and giving Elite armor the new 251 (maybe with Pzgrens).
That works too.
The problem is keeping the radio ability which the 223 replaces in Elite Armor.
But apart from that yeah, Panzergrenadiers or Panzerfusiliers in either a 250 or 251 works, but if it's the 251 I think it's a better option for it to come open-topped because I don't believe they'll give it the same flame projector upgrade.
Edit: Maybe an Urban Assault Panzergrenadier squad in a 250 that can upgrade with an antenna to receive the radio ability combat group and then the 223 can be moved to Overwatch.