I decided to get some specific information for what Badboy was asking.
1) The craft item level (iLvl) is 1/2 your character level + 1/2 the original item's iLvl. If you gambled the ring, then you can assume these are the same, so that Crafted iLvl = your level. If you gamble the ring with a level 80 character, but craft with a level 40 character, then the crafted item will have iLvl (40/2 + 80/2) = 60. This iLvl 60 will be used to determine what mods can spawn in the ring. The iLvl also determines how many mods can spawn. The iLvl must be above 71 for all 4 extra mods. If it's lower than 71, then you have a 20% chance of 4 mods.
2) The
formal formula for crafted item iLvl also involves the item's qLvl (quality level, e.g. Elite items are higher quality than basics). Rings and Amulets have qLvl of 1, so they don't really affect the simple formula I supplied in (1).
3) To get the "of the Whale" mod on a crafted ring, the iLvl must be above 50, so the levels of the character crafting and gambling the ring should add up to about 100 (106 to be safe). Keep in mind that a crafted item's level requirement is about 15 higher than it's highest mod's level requirement, so a ring crafted this way would be about level 65 to use.
If you really wanted to use a level 89 (garanteed access to all mods) character to gamble and craft the item, then the odds of getting "of the Whale" are about 3%. Basically, there's a 24% chance that one of the 4 mods on the craft will be from the +HP group, so it's 1 in 8 that it will be the "of the Whale" mod. Even then, the HP range on that ring will be 196-310 (the odds of over 300 is about 9%), so crafting a ring with over 300 life is about 0.26% or 1 in 400 crafts.
If you use a level 74 char to gamble and craft, then the odds of a +HP ring are 25% (so no change really). It might still be worthwhile to use a level 74 char since you avoid the few high level mods that produce level 99 crafts.
If you used a level 55 char to gamble and craft, then the odds of a +HP ring are 22% (still no change really), since there's an 80% chance of only 3 mods. Still about 1 in 400 to get more than 300 life. The resulting ring should be about level 65.