No, I kept the tank in the same orientation. I cut the center out of part 3 and made a new flat center part using sheet styrene. I then cut one of the tank caps off 3 and sanded it down, then added it to the new center section. I cut down the frame on 3 by the same amount that I cut the tank down (64mm). On the bottom of the tank, I removed/relocated where the pipes come out to the new configuration for an M1062. I also cut out the same 64mm from the frame.
You can kind of see where I chopped the frame here:
Also, I cut the tank just behind the second (from the front) diamond-shaped opening on the top and took out 64mm from there back.
Hope that helps.