Hi Humakt
Michael Perry has said he'll be doing Irish Cavalry, so you may want to see if they look suitable for 14th century?
Not many contemporary images I don't believe. I would expect mounted Irish to be those who are socially superior, so I think I'm expecting mail coats, rather than cloak-wearing kern types. The later Derrick images (c1580s) have them in mail or padded armour, so you could transfer that armour backwards in time.
Cheers, Simon.