How about AD Performance in Washington? I've heard of them in the Popular Hot rodding engine master competition. I am just comparing a stock block 496 -vs- a dart block 572 or 598. That would be the largest size I would go. Thanks for the heads up on Dyno-flo. There are several companies on ebay selling these Dart BBC short blocks. I figure I have $1000 (at least) in machining, balancing, and assembly to use the stock block, and $2000 in the Eagle 4340 496 rotating assembly. If I can spend around $4000 and have a completely balanced, assembled 572 or 598 Dart block with Eagle internals that seems to be a justifiable upgrade. Any other reputable places that you guys want to recommend I would be happy to hear from you.