Actually the C/D variants were built from April thru Sept of '41 with a short-barreled 7.5cm gun (about 200 examples)...the late StuG was the G model and was the most common one seen from 1944 til the end of the war...it was also common because almost 8,000 were built..
So if this is actually a C/D up-gunned at some point and it survived until 1945 it is something of an oddity...I'd say this version is another one of Dragon's "one-offs"...
To answer your question, this is such a quirky example that I'd say you could go ether way on the zimm...