I have no plans for historical units, though I'll probably make some leaderheads.
leaderheads
Here is list of civs with leaderheads (not actual leaders of course):
England - C3C William
Scotland - Robert Bruce
Celts(*) - gael's King of Stathclyde
France - Joan
Germany - Otto
Burgundy - Medieval Alexander
Castile - PTW Isabella
Aragón - utah's Spanian
Portugal - C3C Henry
Tuscany - C3C Charles
Venetia - Medieval Ceasar
Sicily - gael's Norman
Bohemia - Medieval Brennus
Poland - Piernik's Casimir
Teutons - my Karl-Franz
Denmark - PTW Ragnar
Sweden - Medieval Hannibal
Novgorod - gael's King of Connacht
Kievan Rus - my Zoltan
Lithuania - gael's King of Wessex
Hungary - utah's Stephan the Holy
Bulgaria - my Barbarian
Byzantines - C3C Theodora
Turks - PTW Osman
Armenia - gael's King of Powys
Mongols - PTW Temujin
Abbasids - PTW Abu Bakr
Sassanids - Medieval Xerxes
Saracens - Ancient C3C Mursilis
Almohads - Medieval C3C Gilgamesh
Moors - Medieval C3C Mursilis
* - I think starting just before crusades in the Levant will offer more attractive gameplay ie. with VP scoring like in c3c conquest. This is of course discussable... Celts were the first choice to replace Levant. They may start in Ireland, or have cities pre-placed in Ireland, Scotland and Wales.
One leaderhead is duplicated, so making a leaderhead for Saracens or Moors is priority. Then maybe Armenia and Bulgars. I'm not sure if they will be made after any specific leaders, but I'll try to use proper clothing, backgrounds etc.
map/resources
Currently using large europe, with correct swamps/volcanos, some sea/ocean adjustments, no warhorses (I didn't like the idea), but with "game" back. I also added salt in baltic and mediterranean (works as a bonus resource in this case), and turned gold from luxury to bonus (salt, wine etc. really made people lives better, but did gold? it's just wealth. there seemed to be too much luxuries too). Added Wool in Wales and Ireland and similiar minor changes. Now, feel free to put these down...