Yes,
within limits of tolerance variation, this is true of the upper assembly.
You asked if the barrels can be "swapped" also, again the answer is yes; though with regard to barrels you have to deal with the lenght of the threads and their corresponding chamber lengths.
Most 1906 are the same as the 1908, with short frames. There are a few exceptions. Navy lugers are not 1906 models, but 1904 and have long chambers and barrels, until you get to the '1914" model, and a couple other scarce exceptions.
The moral of this tale is you need to be specific on what you want to do and post pictures of both the upper or receiver and barrel you want to use.
Barrels may or may not "time" when changed, or headspace may need correcting.
Your question is more complicated than it seems.
Below are pictures of a long shank navy barrel on a short receiver using a space ring, the receiver is a reject WWII Kreighoff on a 1904(1906) navy long frame. Result is a hybrid for sure but a semi-navy looking shooter clone.
