Yes, a good, used factory system beats a rotted out setup. I put on an OE used rear muffler on my 300SD years ago from another junkyard SD. Works fine to this day. The middle resonators are usually longer lasting than the rear mufflers on city cars as the resonator will become hot faster and getting the water out.
My 560 has a stock catback from 1991, I would not hesitate to install on another car and run it. SDL too. I own multiple E23 BMW 745i, I have fixed many botched exhaust systems on them with good, used OEM Boysen resonators and mufflers produced in the 1980s.
Interesting OE Eberspacher is NLA.
In any event, between Bosal and Ansa? I would go Ansa.
Do not forget about checking Timevalve -
Timevalve Manufacturing - Stainless Steel Exhaust Systems and Catalytic Converters for Mercedes Benz, Vintage Ferrari, and other Classic Cars Unsure of cost, but they are stainless.