I have a PR6 news related website with over 300 basic pages indexed (well over 100,000 in the domain, but the exchange only applies to those main 300 basic pages, and possibly 30,000 others).
Main site - PR6 - 300 pages
Forum - PR5 - 30,000 pages
The exchange I would ideally do would be including your link on my news site
on those 300 pages, in exchange for an appropriate number of links in return (not too bothered about PR, as long as it is pr3+, and in those cases, quite a lot of links in return). This link would go to one of my other sites (i'll give you it in the PM). This way of exchanging minimises the risk of Google penalising for a site wide link exchange, as the link won't be returned on your site.
I am also willing to do a similar thing on the forums
as long as it is a similar number of pages.
If you are interested PM me, if you want to confirm something or ask something, do so in the thread.