Welcome to FBBO from NorCal Sierras
Not knowing the details or any more detailed photos etc.
Being garaged it's whole life a serious plus in the north
& only 30k miles
I'd guess, (?) $15k if light noticeable surface rust here or there
in some of the spots noted prior
& as much as $20k - $22k-ish if mostly solid maybe
Satellite Sebring was a notch-up, but base model with a
318 2 bbl org.
904 Torqueflight 3 speed trans, column shift auto,
8.750" (?) rear etc. (2.76:1 or 3.23:1 with a sure-grip)
the nonfactory 4bbl intake/carb, dual exhaust & different wheels,
won't really hurt the value, it will give it a bit more pep too
(I'd still get, if they are still available, all the org. parts that came off too)
clean interior, I assume probably a bench seat/cloth w/headrests, if no rips
if it has a console & buckets, power windows or has A/C
definitely a step up, in options then $25k+ possibly
(worth more, you could add another $1,000-$3,000)
if it is as solid/nice as it looks in that 1 photo
good luck