Andrew,
those are fantastic news! It's just a bit unpleasant that we didn't come across each other in the forum sooner because the location and date has been much speculated.
So if it's a 1938 vehicle I guess it's not already in overall panzer-grey, probably in a 2 tone squeme instead. A couple of ML members told me that it was a Magirus chassis but in 1/72 scale the difference in about 2mm so I just left it untouched. However I think the front grill and mudguards should be changed to those in the next picture.
If it's possible for you to show me the photo it'd be most appreciated. This little build has been turning into an excellent research project, and even if my model doesn't make it justice, it has been really fun so far!
Thanks again to everyone that showed their interest and left a comment, I appreciate it.
Here are a couple more photos that show a bit of the progress:
I started to carve the bottom block of plaster first, the road one. Carved the road section so it'd get lower than the sidewalk part and made the several rows of "tiles" with a little and thin ruller made out of aluminium soda can ( has it could be cutted like I wanted and was more flexible). I did the same thing to the wall, carving the tile section first so the sidewalk could stand out a bit. Then I carved the tiles in the wall and the top sidewalk itself. The sidewalk grill was made out of copper wire with the help of a "third-hand", one of those magnifiers with two clip-ons.
Thanks again for all your help!