Some LS Montes came with bucket seats and console like the SS and Aerocoupes. But on this same note, some SS and Aerocoupes came with a bench seat.
Like mentioned the SS has blacked out stainless.
There were only two rear spoilers off in 1986 that I'm aware of the stand up and lay down styles. So either will work on your LS.
If you're building an engine for your car then you're way ahead as far as that goes. My LS had the original 305 scrapped by the guy I got it from. He paid someone $850 to install a used 305 H O under the hood. It's still a decent engine so I left it alone.
No real numbers from GM/Chevy to go by but most seem to think there were less LS Monte produced then the SS body so I've left my car alone.
I have tried to make the car a decent car again after the abuse it took. And I've added things to make the car mine.
Such as an SS steering box and rear sway bar. My LSalready had the larger dia front swaybar and triangular bars up front.