The group exits the caves into a similar but strangely different world. They feel different and the world around them somehow looks simpler. You realize that this universe operates with different rules.
You might find the slightly older “light blue box” 1982 2nd edition Expert rulebook to be easier to use.
Afarrah becomes a suli-looking human cleric.
Pugno becomes a human fighter.
Shivs can go the 6th level elf route (but without a spellbook that is a problem) or her human side can prevail and be an elven looking human cleric or human fighter. There isn’t multi classing in Basic. (Joe will be out for 2 sessions though)
Shok can convert to either an orcish looking human thief or an orc with the chieftain stats (15 hit points, who attacks as a 4 Hit Dice monster and gains + 2 on damage rolls.).
Tiffany can choose to convert to a fighter, thief, or magic-user. If you go the magic user route though she doesn’t have a spellbook to memorize spells from so you’d be hoping to make it back to Absalom the same day..
Weiss is stuck in whatever human form she was disguised as and becomes a human thief.
1) Convert over based on level of course and figure out your new proportional XP total too since you’ll be earning DnD Basic XP for multiple sessions. Hey there is a bonus to experience now based on your Prime Requisite!
2) Racial maximums apply to ability scores. So no stats above 18 ( I don’t remember if there are any other limits).
3) Don’t overlook the new ability bonus spread: The breakdown is
3 = -3
4-5 = -2
6-8 = -1
9-12 = 0
13-15 = +1
16-17 = +2
18 = +3
3) Adjust HP by adding or subtracting 1 pt for each die difference. So if Afarrah goes from d8 to d6 for hit points she’d lose 1 hp (the average diff between rolling d8 and d6) per level. Don’t forget that Con bonus ranges change in Basic/Expert.
4) Cleric spells. You can only keep spells that exist in the B/X rules and you are probably losing spell slots but you get to pick what you keep and lose at least. You still have a connection to your god so the next day, if there is a next day, you’ll be able to pick from the cleric list.
5) Characters look and are equipped the same. Potions and scrolls of spells that don’t exist remain magic but are inert.
5) Weapons: Scimitars do d8. Rapiers are d6. Falchions are d10.
6) Armor: Studded leather just becomes leather AC7, chain shirts are AC 6, and a breastplate is still the same as chainmail, AC5. Shields lower the AC by 1.
7) Unarmed strikes do d2
8) Magic armor weighs half as much.