When you say penguin update...which one? What date as penguin has had several updates so you need to be sure?
A lot of people "legitimately" over-optimised in bound anchor text as there was no penalty for it. In your case you have no site-wide links (from memory) that you can cull in one go and make a big difference in one go.
I think you need a full site audit first to identify the date that the penalty took place and then make a strategy to part grow yourself out of the penalty and part identify high affecting anchor texts but low value links and get them removed.
I can't remember when looking at your site several days ago if most links go to your homepage or deep pages. If they go to pages other than your homepage (and the penalty is confirmed as an over-optimisation penalty) then you could let those pages 404 and remake them elsewhere on the site.
There are plenty of people, myself included, who could work with you on this and I think Marcus has mentioned that he also does site audits and from reading on this is Marie also has experience of identifying penalties and taking corrective action. You may already have enough knowledge and experience to do this yourself but if not I think the first port of call would be a site audit and identification of the penalty.