Is it even worth trying to sell a 741 case??

They get such a bad rap.Nothing wrong with them. At one time gears were available and had 4.30's in my 67 Dart. I think Dr. Diff sells 3.73-down for them..
The last ones I've sold I got $25 for open 741's.

What he said; they get a bad rap, only problem with them is lack of gear sets; lots of OEM 2.76's, 3.23's, aftermarket I beleave has 3.55's and 3.73's. Look under old /6 pick up trucks; might find 3.55's, 3.91's, 4.10's. Think about it, if they put them under pick up trucks, how weak can they really be; farmers I knew were NEVER shy about how they used/abused their pick up trucks (3 ton of feed on a 1/2 ton truck).

I got a set of 4.88's from some one who didn't know what they were, set them up on a spool for racing

They have value, don't let some one BS you other wise