You could spend an age looking for correct movements and not see a return greater than you could get for movement and case/dial separately.

I suspect selling so many is not going to be the work of a moment anyway, so the sales approach is likely to be phased anyway.

If it was me, I would first put the cases up for sale singly, stressing the provenance, and look for buyers who are restoring or looking to complete a specific watch.

That will whittle the numbers down a bit.

Then I'd consider discounting for multiple purchases - x% off for the second case, x+5% for the third etc and you'll probably pick up some buyers who are looking to resell. They might make more of a profit but you should still see a decent return and won't be sitting on such a large stock.

Finally, whatever is left at that point, I would look to mate with movements and sell as a complete watch, though stressing it was built from a salesman's sample bag. Nothing to stop you doing that as and when you find movements during the "other" sales too of course.

That's how I'd see the most sales for (relatively) little effort; although probably not the largest profit, it should be quite efficient. I think you'd be unlikely to find a buyer for the whole lot, but you never know - discount it attractively while building your return in and someone could bite.