At a recent AC I was asked to rank 3 of the others I had applied to other than the firm itself and why!I think being specific where you can is helpful and persuasive, but there is a balance to it. I think you can just reference one (possibly two firms) but ensure they are most closely aligned to the firm you are applying to.
In your situation you could say something like “Having enjoyed the work I completed at Joe Bloggs LLP, I am interested in firms with a strong project finance practice”.