would like to buy complete feather duster or dart lite (1975's), preferably western u.s
I grew up in WI, I owned 2 Feather Dusters (both OD cars) and the problem your going to find is that there were only 1,500 of each Dart and Duster and they were only sold in 6 Midwestern states new from what I learned back in the day.
I looked at one out here in CA about 15 years ago that was an original IL rot bucket and another in OR that was from OH and pretty much the same. Texas was the early Silicone Valley (Texas Instruments) and a lot of people up north moved down in the early 80's so you may find one in decent shape there that probably already seen rust but not as bad as others. If you find a clean one you'll be lucky, most are rusted and picked apart for the lightweight parts. BTW, the hoods are actually ugly with the inner braces riveted in, the trunk lid is better and it's funny that they damn near take your head off when you open since they used the same trunk springs and it weighs about half.
The one I ended up restoring got 31 mpg when I bought it. I replaced both quarters, extensions, trunk pan, floors and fenders and that was in 83. Back then I had to get OEM parts from AZ at pricey shipping costs since there were no repops at the time. I think I paid $800 in truck freight, if I remember right. I did own it for about 10 years, drove it to CA in 1990 and it got smacked hard in a T-bone accident in 91 so it's gone. I ended up replacing it with a 74 Space Duster at the time w/ a 318, A/C, buckets and no console. I sold that one in 98 and I suspect it's still roaming the streets of San Jose.
Good luck my friend, John