Get an independant M-B guy and pay him a couple of hudred dollars to check it over.
450's are quite common and $1200 is not particularly cheap or particularly expensive.
Cruise control will probably be a new amplifier - do a search on this site.
Windows may be motors but may also only be dirty switches.
Rust is the biggest problem - get this checked very carefully.
They were expensive cars and cost a lot of money to put right and at the end of the day it may still be only worth $1200 but you just might have had a lot of fun.
Biggest shortcoming is the timing chain and tensioner on a 450.
Bill
Thanks for the quick reply Bill

I have considered getting someone out to look at it...but my previous job was working on and repairing trucks...same kinda thing I guess

including respraying and body work etc...I wouldn't be doing the work on this kind of car...but I do know what to look for.
Underneath she looks clean...not really any oil build up that I can see...just the usual kind of 30 years of road grime build up...
All rust that I could see is really surface rust...nothing too deep that can't be fixed with some elbow grease and the right materials.
I'm not sure about the cruise control...but I will look around as you suggested

With the windows...the drivers door works fine...the front passenger motor sounds very noisy but the window doesn't move...and the back ones don't make any sound or movement at all.
If I was to buy and fix up the car..I would with all intentions have it for a long time...so I'm not too concerned about re-sale but thanks for mentioning it

As I mentioned above I know my way around an engine so any work/repairs I can do.