Eric,
Ok, this is where things get tricky because we are using a "modeler" designation instead of an actual designation...you have to define what set of features you mean by "late" as the StuG III G production continued to receive modifications to the end of '44 and appear unevenly in production into '45 as a result.
Generally speaking, the Imperial #9014 represents a "final" configuration and is still the only DML kit out there that has the remote roof-top MG mount and revised roof hatches, those were introduced in April-May '44 and onward. It also features IIRC the saukopf mantlet with the coaxial MG port which was introduced in Oct '44 and the heavy duty tow-bar introduced in Dec '44and therefore post-zim timeframe.