3 70 4 doors (tan, green, and YES ! BLUE )in local yard; don't have my resource notebook with me as to interior trim. I may be going there next week. https://www.google.com/maps/@34.6558881,-79.5177306,440m/data=!3m1!1e3
I recovered my seat in my 70 gs afew years ago and had to look for some. I think I may have extras.give me a day or so to look for them.
I looked also.cant find any yet. Pretty sure when I purchased some from Duane, I had more than I needed. I'll keep looking.
There was a Chevy Pick-up that used buttons that were very close to the 70 Standard Buick buttons you need. You might want to look into that. They might be reproduced, or at least easier to find. There is also a special tool that you will need to pop the buttons off the backing plates. If you do find some, you can send them to me and I will pop them apart for you. If you don't use the tool the backing plates usually break at the cut lines and then you have a problem. The backing plates make the buttons "sink into" the seat covers. Duane