This is my first link and a rather handy one at that. It's website in both French and English covering a vast array of early blazons (as the name suggests) with the heraldic designs of just about everyone I have come across to date.
It also has a very handy battle index with key people present and their arms. It is accompanied with a basic precis of each battle. Whilst my research is more comprehensive, it is nevertheless a very handy place to begin and I recommend it highly for anyone embarking on a similar battle-build in this period.
If it's still running by the time I get to the so-called First Barons War, it will be one of my first ports of call.
Early Blazon: Lewes
I don't seem to be able to link you straight into the Lewes chapter, so just click on 'Battle' link in the left margin and pick your battle.