Back in the day, a common swap was to install a Model Power/Mehano FA2 shell on the old Atlas/Roco FA1 drive, which was far superior to the Yugoslavian garbage.
This set was done by David Lloyd of England, who donated them to the WMRHS N scale Layout fleet. We ran the devil out them.
On close inspection you can see the gaps behind the pilot and ahead of the rear ladder, since the shorter drive is centered under the shell. If the newer locomotives you're talking about are accurately scaled, you should be able to get away with a similar illusion. The tricky bit will be how the shell fits on the drive. The old dogs didn't have much in the way of little nubs or protrusions on the inside, just the clips down by the fuel tank. As I recall, there was some weight added over the drive to improve pulling performance, and the longer shell provided ample room to do so.
It helps if your paint scheme is basic black, so keep that in mind...
Lee