Scott,
You got a lot going on here.
Not sure how to describe this,
it looks like you have authentic
parts from various speedmasters,
along with parts that are not authentic.
I tend to agree.
It looks like the back is authentic (Omega)
but maybe not "correct" to this watch.
(In "our" language, the back that originally
came on the watch would be both "correct,"
and also "original to the watch.")
If the back is "not correct," it can still be OMEGA.
The case MIGHT be an early Speedmaster
that has been "bored" for the moon and
the date function pushers.
Omega non-the-less ?
I am willing to believe the "motor"
is an authentic OMEGA movement,
and who knows....original to this case ?
Almost certainly the dial(s) and bezel-insert
(notice the slight language change) have been
refinished. Not a terrific job, but OK
for the 1990's. on a (max) $1,000 watch.
Here's an interesting line of inquiry:
How "REAL" is this watch ?
(Momentary segue.....In motor bikes, we have
certain rules:
1) If you have a frame, you have a bike.
a) The VIN and the tag and title go with
the frame.
b) Motor has a number, but is NOT by definition
the bike, 'cause motors - like movements - can
be changed INTERNALLY, with no outer signs.)
Right now, without "pulling the movement(s)",
what we see is this:
1) Back almost certainly Omega.
2) Case almost certainly Omega.
3) Crystal and Bezel Omega underneath the re-finishing.
4) Visible movement OMEGA.
So: So far we see a lot of stuff that is
either INCORRECT for this watch,
or has been refinished, or has been modified.
It's maybe ALL Omega parts, but certainly
Omega never saw it in that form......
Kind of like a 1934 Ford, with NASCAR brakes, VIPER drive train.
It's a "Vintage Hot Rod."..........