Here are two Library's that are in Jamestown. If you contact them they might have the newspaper articles concerning the Swedish Exchange Students moving to that area. (The Library usually will do the lookup for you for a small fee)
Sometimes the articles even give the NAME OF THE FAMILY that the students lived with at the time, and you could look up the name of the family at "whitepages.com" to see if they still live in that area. Someone in that family just might have stayed in touch with Peter Lindgren all these years.
You might also ask the Library if they have a yearbook from 1983 (if that is when he graduated) and how you can find the names of the students from that year.
I would also post to the Chatauqua County Jamestown Rootweb Message Board and ask if anyone knew him.
Then I would post a seperate message. I would make sure I put in the subject line "Anyone with a 1983 Jamestown Public High School Yearbook for lookups" that way you could have them either give you the names or scan the pages and send them to you of the male students and then go to whitepages.com and see if they still live in the area. Maybe some of them remember your birthmother and birthfather.
FLUVANNA FREE LIBRARY
3532 Fluvanna Ave. Ext. Jamestown, NY 14701
Phone: (716) 487-1773
Fax: (716) 487-2311
Hours: Sun Mon Tues Wed Thurs Fri Sat
Closed 10-8 10-6 10-6 10-6 10-8 10-2
Hazeltine Public Library
891 Busti Sugar Grove Road
Jamestown, New York 14701
Mon. 1 p.m. - 5 p.m. & 6:30 p.m. - 8:30 p.m
Tues. 9 a.m. - 5 p.m.
Wed. 1 p.m. - 5 p.m. & 6:30 p.m. - 8:30 p.m.
Thur. 9 a.m. - 5 p.m.
Fri. 1 p.m. - 5 p.m. & 6:30 p.m. - 8:30 p.m.
Sat. 9 a.m. - 1 p.m.
This is the website for Chatauqua County N.Y.
If you know your birthmothers family name you might find information here or if you want to post to some of the sites here to look for family you can also do that.http://www.rootsweb.com/~nychauta/
Have you posted to the surname boards for the name "Lindgren" ? If they don't have a board with that name you can request one.