Came across some potentially useful Volvo documents, which I thought would be worth sharing:
1983 B21ET Gp.A-spec assembly + Gp.A homologation papers
http://hyperfileshare.com/d/40be92b1
...and 2 RSport catalogs from I don't know when.
http://hyperfileshare.com/d/a6095ef0
http://hyperfileshare.com/d/2c1cb2a1
Hope they'll be of some use.