Is there a listing how the basic classes were created using the custom class system?
Not that I’m aware of, but you can derive most of them pretty easily.
Off the top of my head:
Fighter - Fighting 2/Hit Dice 2.
Mage - Arcane 4.
Cleric - Fighting 1/Hit Dice 1/Divine 2.
Thief - Fighting 1/Thievery 3.
Assassin - Fighting 2/Hit Dice 1/Thievery 1.
You can always tell the fighting value from the attack throw progression, even if they traded away weapon and armor proficiencies. Hit dice is equally easy to figure out. Thievery can be the hardest to pin down if they traded them all away for custom powers (like the Explorer did).
Bard - Fighting 1b/Hit Dice 1/Thievery 2.
Bladedancer - Fighting 1a/Hit Dice 1/Divine 2 (trade down armor selection to Narrow for initiative bonus and Swashbuckling).
Explorer - Fighting 2/Hit Dice 1/Thievery 1 (trade down armor and weapon selections to Broad for abilities).
Dwarven Vaultguard - Fighting 2/Hit Dice 2/Dwarf 0.
Dwarven Craftpriest - Fighting 1/Hit Dice 1/Divine 2/Dwarf 3.
Elven Spellsword - Fighting 2/Hit Dice 1/Arcane 1/Elf 3.
Elven Nightblade - Fighting 1/Hit Dice 1/Thievery 2/Elf 2.
Anti-Paladin - Fighting 2/Hit Dice 1/Thievery 1, trades off weapon selection for more abilities.
Barbarian - Fighting 2/Hit Dice 2, bunch of armor & weapon trade-offs.
Dwarven Delver - Fighting 1/Hit Dice 1/Thievery 2/Dwarf 2.
Dwarven Fury - Fighting 2/Hit Dice 2/Dwarf 0.
Dwarven Machinist - Fighting 1/Hit Dice 1/Thievery 2/Dwarf 3.
Elven Courtier - Fighting 1/Hit Dice 1/Thievery 1/Arcane 1/Elf 1.
Elven Enchanter - Fighting 0/Hit Dice 0/Thievery 1/Arcane 3/Elf 1. (But the XP total is 2700 instead of 2825; the difference is equal to the XP value of Elf 0, oddly.)
Elven Ranger - Fighting 2/Hit Dice 1/Thievery 1/Elf 0. (XP value should be 2,425 instead of 2,275, because they trade down Unrestricted weapon & armor to both Broad.)
Gnomish Trickster - Fighting 1.5?/Hit Dice 0/Thievery 2/Arcane 1/Gnome 1. (Weird case; they attack as thieves but save as fighters.)
Mystic - Fighting 2/Hit Dice 1/Thievery 1 (pile of trade-offs).
Nobiran Wonderworker - Fighting 0/Hit Dice 0/Arcane 4/Nobiran 2 (Heroic Spirit puts their maximum level back to 12th).
Paladin - Fighting 2/Hit Dice 1/Thievery 1, trades off weapon selection for more abilities.
Priestess - Fighting 0/Hit Dice 0/Divine 4.
Shaman - Fighting 1/Hit Dice 1/Divine 2 (trade off armor & weapons).
Thrassian Gladiator - Fighting 2/Hit Dice 2/Thrassian 2.
Venturer - Fighting 1/Hit Dice 0/Thievery 2/Arcane 1. (So far, almost all of my setting versions trade out Arcane 1 for Hit Dice 1.)
Warlock - Fighting 0/Hit Dice 0/Thievery 1/Arcane 3.
Witch - Fighting 0/Hit Dice 0/Thievery 0/Divine 4 (trade away turning undead).
Zaharan Ruinguard - Fighting 2/Hit Dice 1/Thievery 1/Zaharan 2.
Randomly, I just noticed 7th-level anti-paladins are Wardukes. Awesome reference.
Elves reduce the cost of Arcane value by 125, which is the same as Elf 0 costs.
So there is no difference between Elf 0/Arcane 4 and Elf 1/Arcane 3; both of them cost 2500 xp and give you full spellcasting.
As a result, Elven Enchanter is 2500 for the full spellcasting (whether it’s Elf 1/Arcane 3 or Elf 4 or Elf 0/Arcane 4 or any other combo) plus 200 for Thievery 1 gives you 2700.