Hello,
if I remember well all "previous" quests are stored inside the gameserver itself (picture below). There is no known guide to change them (at least I am not aware). You can search for "QNO" with olly to find them at least. Only few quests were changed into lua during quest update at 100lv cap (introducing the new format).
Maybe there might be a way to disable and recode a copy of them. But some quest types like "use items at position X" (e.g. zerk quest) are still unkown in lua. You can only use delivery, hunting (daily/chain), collecting items , dialogue and fgw collection book type using lua.
Cheers
