Sounds like you want early 14th C. gear. The ultimate armoring resources for 14th C. are TOMAR (Techniques of Medieval Armor Reproduction, the armorer's Bible, essentially) and the Armor Archive (they have a TON of people that do 14th C. over there). I, in fact, am always working on my own ~1360s kit (my SCA rig).
Attaching maille sleeves to a CoP sounds like a bad time; it wouldn't ride right. It's plausibly period to wear a shirt of maille that only consists of sleeves and enough body to attach them to one another, though, if you want to wear something like that underneath of the body armor.
Look at effigies and paintings and reconstructions of European warriors from 1300-1380 or so to get an idea for what armor was being worn with what during various parts of that period; It would certainly be reasonable, during portions of that time, to wear a hauberk, CoP, spaulder, rerebrace, couter, vambrace, gauntlets, cuisses, poleyns, and fully-cased greaves (or at least shynbalds), plus sabatons, probably with a bascinet or cervelliere (over a maille coif).
Here's a pretty cool meta-analysis of English effigies of the 14th C.
http://talbotsfineaccessories.com/armour/effigy/English-Effigies.htm with neat charts showing the kinds of harness components worn during various decades (of effigy date; this isn't necessarily exactly right for what was being worn when).
As far as garb goes, The Medieval Tailor's Assistant is a great reference of plausibly period construction methods that produce (allegedly; I haven't made anything from my copy yet) very good, correct-looking garments. It covers 1200-1500, including a variety of surcote and jupon options, as well as doublets (which are very nearly arming pourpoints in their own right), cotes, tunics, cotehardies, and gowns.
If you can find the Osprey military history series of medieval men-at-arms and knights, you may find some decent pictorial references.
