No, I mean there should be an open ramp rear sight mounted to the top of the receiver (normally mounted on the barrel). The Mossberg scope/mount wouldn't have been original.
Yes, the sights in post #4 look like one of several different versions of rear sights I saw as well.
I have one.
They were made shortly after WW2 and went by a couple different names for different store buyers.
The original rearsight is a battle peep type .
Under the handguard , there should be the groove cut. out for the rearsight that's found on all Stevens 87 series rifles.
It will likely be stamped Steven's 87A under the handguard as well.




























