As you can see in the shot below, I've cast a copy of the hatch to use as a donor for the vehicle. I then sanded off the existing machine gunner's hatch and replaced it with the resin cast one in the correct orientation for the Ostwind.
Here's a group photo from another angle showing the orientation of the hatches. I did have to re-scribe the line between the front hull armor plate and the top armor.
So far I've converted three, which is probably all I'm going to run for my 512th army at any one time. I have at least one more Ostwind still in the blister that will undoubtedly call to me some day.