Ed, the small parts can be interchanged without problems. Even the complete toggles just slip into place. Same goes for the Mauser Parabellum, really. I've even put MP parts on a P08 and vice versa.
The main problems are with the barrel/receiver combination and the frames. An 06/29 Frame will work with an 06/29 Barrel/receiver combo, but not with much else
postscript:
It may be a fun test for someone with the parts at hand:
-Assemble a 1906 Swiss barrel/receiver in .30 luger with an 06/29 frame: Test it.
-Assemble a DWM 1906 or 08 style barrel/receiver combo and test it using an 06/29 frame.
-Repeat with several barrel lengths.
Mauser found problems with the following combinations:
-06/29 toggle ramp combined with 10cm .30 luger barrel.
-06/29 toggle ramp with 15cm / 10cm 9mm barrel.
That is why the initial Mauser Parabellum came in .30 luger with a 15cm barrel.
ps: the X on Guisans scans means 'not available'. I guess that the person who compiled the list had no data available for those particular parts. Rough translation of the header:
Exchangeability of the parts of the three Swiss Army Pistol Models 1929, 1906, 1900.
Table:
- = can be exchanged/swapped.
blank = Cannot be exchanged/swapped.
X = Not available.