So, we decided to wing it on the pattern. We bought linen and I stood there in gambeson / maille / breastplate to get the proportions right.
I decided to go with felt for the charges and we'll sew them to the base garment. We may add some detailing to the charges using sewn on black thread, but we'll see. Aside from sewing on the devices, we need to add lacing eyelets on the side to give it the form fitted look of the late 14th century. Since there were no such thing as metal eyelets / grommets like a modern garment would use for lacing, I'm undecided if I want to try and do this the hand-stitched way, which is a giant pain in the butt, or just use metal eyelets. But this is where we're at so far:
Hahaha, and I realize now that I laid the crossed swords on upside down... good thing my wife didn't sew them on yet!