As I mentioned, I'm using almost the same fields as you are for AD&D. I'm attaching a screenshot and a stat block. I'll be adding a bit to each stat block so fit with the NPC fields, such as size, # encountered, intelligence, treasure, base to hit, etc.
Attachment 17887
Demonic Knight
Hit Dice: 9
Armor Class: -1 [20]
Attack: +1 longsword (1d8+1) or 2 slams (1d6)
Saving Throw: 6
Special: Breath of unlife, fear, magic resistance (30%), +1 or
better weapon to hit, spells, summon demons
Move: 12
Alignment: Chaos
Challenge Level/XP: 14/2600
Add:
Size: Medium
# Enc: 1
Intelligence: High
Treasure: TBD
Base To Hit (based on THAC0): 10
Does that give you enough to go on?