If I were you I would refurbish it but do not convert it to single speed. as Stu F said, just change the cables if they are worn out, and as for the brake calipers, just autosol them and they will come up nice and shiny. I would also remove the mud flaps and the bike will get a more sporty look.
Hi, great bike you've got there :), it is also very very similar to mine (see below link), mine is a Raleigh Team Europa 1979.
http://www.lfgss.com/thread90168.html
If I were you I would refurbish it but do not convert it to single speed. as Stu F said, just change the cables if they are worn out, and as for the brake calipers, just autosol them and they will come up nice and shiny. I would also remove the mud flaps and the bike will get a more sporty look.