It was my understanding that Steve Lamboy had the rights to make Lefevers, which he acquired when he set up Ithaca Classic Doubles. Unfortunately ICD is now out of business and the Ithaca name has changed hands a couple times since. So who owns the Lefever name now??
My feeble understanding of patent and copywrite and trademark laws is that nothing can prevent someone from reverse engineering a product that the patents have run out on or never existed. As for trademarks, that's a different subject and the laws seem to last forever or at least that's my perception.
So, an example of this is the 1911 Colt design. A bazillion copies are made and marketed.
I beleive there would be no legal issues with producing an exact copy, but the name may not be available if it has a valid trademark.