Say I was going to fully build out these pages with content, how much unique content should I have per page (minimum)?  Would several paragraphs do the trick?

I have a client that does website contract work for about 50 governmental county websites.  The client has the ability to add a link back in the footer of each of these websites.  I am wanting my client to get backlink juice for a different key phrase from each of the 50 agencies (basically just my keyphrase with the different county name in it).  I also want a different landing page to rank for each term.  The 50 different landing pages would be a bit like location pages for local search.  Each one targets a different county.  However, I do not have a lot of unique content for each page.  Basically each page would follow the same format (but reference a different county name, and 10 different links from each county website).

Is this a good SEO back link strategy?  Do I need more unique content for each landing page in order to prevent duplicate content flags?