Hi Templar Knight
Check out this link, it's Christian Tobler's arming sequence guide to "How a man shall be armed when he fights on foot" dated 1450, but equally suitable for 1370. In fact Christian's harness is just about perfect for your timeline anywhere between 1370 - 1390.
http://www.revivalclothing.com/index.as ... stom&ID=15
The guide is listed on the US company 'Revival Clothing' site. I use a Revival Clothing pourpoint (arming waistcoat) and gambeson (arming coat) to tie my harness onto.
You tie your plate armour legs to the bottom of the pourpoint (it is very important to tie them firmly so the legs don't drop at all or the knees of the legs will not bend properly). Your plate arms and shoulders are tied to the sleeves and shoulder of your arming jacket.
The only item that Christian is missing in his arming sequence is his Haubergeon, the half-sleeved maille shirt which goes over the top of his gambeson.
For your shopping list I would suggest:
nice pair of knight's ankle boots;
pair of single-legged hose;
pair of Braies (big baggy medieval boxer shorts) you tie your hose legs to your underpants!
linen 'St. Louis' type shirt;
A dozen arming 'points', honey waxed braided laces which will not slip when tied, you tie your armour on using these points;
An Aketon (this is your gambeson but aketon is the proper name for this garment when the maille goes over it not under it);
Haubergeon - maille shirt which falls to about top of thigh;
Sabatons - armoured feet to go over your boots;
Greaves armoured shin and calf guards;
Cuisse & Poleyn - plate armour thigh and knee;
Breastplate - Christian is shown using a Churburg no. 13 segmented breastplate which is fine for the period, but these babies are quite rare and it might be better going for a Churburg no. 14 instead;
Spaudlers plate armour shoulders;
plate arms - as Christian is using;
Heraldic jupon surcoat (optional)
14th century sword, belt and Rondel dagger;
If you need any other help please feel free to PM me
Pic of me in my late 14th century knight's harness attached.