On the issue of firing the .45 ACP in the longer chamber:
With some years of gunsmithing to include re-barrelling and re-chambering well behind me (by a couple of decades)...
IMHO, while it may be true that the firing of such a combination may not be "reliable"... it would certainly be safely possible, and the taper of the .45 ACP case dimensions, would also lend itself to providing an "alternative" headspace surface that would likely hold the case sufficiently for the extractor to slip into the extraction groove... There would be plenty of headspace friction between the cartridge case and the chamber, and the holding power of the extractor should not be overlooked.
I would personally have no problem attempting to fire the .45 ACP round in the longer chamber.
Somebody send me their .45 Test Luger from the trials, and I will be happy to make a video of me shooting several boxes of modern .45 ACP ball ammo through it and post it here. I would even pay the return postage to send it back to the generous collector who would take me up on this offer! 
Also
IMHO, My friend Dwight Gruber's analogy to the Astra 400 mentioned previously is quite valid... shooting shorter cartridges in a longer chamber may not be recommended practice, but it also isn't much of a problem. While the revolver cartridges are headspaced on the rim, Shooting .38 special in a .357 magnum chamber, and .44 special in a .44 Magnum chamber is done all the time.