If you have a 904, build it yourself, it's NOT hard to do. Building an engine is harder to do than a 904 or 727. Plus you learn a new skill and don't have to rely on someone else to do it anymore.

There are a bunch of videos, books and a really strong recipe cost about 300-400 for all the parts, many of which can be used over. One of my friends has this build behind a 525ish hp stroker hitting it with a 100-150 shot.

http://www.forabodiesonly.com/mopar/threads/904-race-tranny-recipe.256475/