Someone posted a similar list for EXP calculation in S2
in this thread. My calculations are based on it. The exp distribution the same, except for the "invisble" levels of the enemies. The strategy guide lists the enemy Lv for S2, and the list fits here, so I suppose it works the same way for S1. You just had to adjust your level's by 2, which makes the Holly Boy Lv 3.
EXP are worked out for each char on it's own.
The formular for S1 is:Total EXP += EXP (based on your lv) for each enemy
Total EXP = Total EXP / Number of party members
if (Total EXP < 5) then TOTAL EXP = 5
if (Fortune rune equipped) then TOTAL EXP * 2
The formular for S2 is:Total EXP += EXP (based on your lv) for each enemy
Total EXP = Total EXP / Number of party members
aliveif (Total EXP < 5) then TOTAL EXP = 5
if (Fortune rune equipped) then TOTAL EXP * 2
Therefor, the Fortune Rune trick is much easier in S2.
In theory the max EXP is 120.000. 1 party member with Fortune rune and 6 enemies which are 15 lv superior than you. That cannot be done here, because it would require a Fortune Rune on McDohl. When you are able to equip it on McDohl alone (at the very beginning), there are no enemies with the required lv. Tested: The best group of enemies are 6x Slasher Rabbit on Mt. Tigerwolf that are around ~7-9 lv superior than you.
So obviously, 60.000 EXP are the max with a two-man party. Refer to my post on the first page for further details.
@Ellyos: A complete list for the enemies' lv for be a great contribution
But please open a new topic for that, as this one is mainly for the level building.
@True Griever: 255 is max for all base stats. Bonuses given by equipment and/or runes may exceed this limit.