The World block has a slightly chaned oiling system. They are the least expensive of the aftermarket blocks, something around $2500 from your local Dodge dealer.

The KP-440 block from Koffel has a priority main oiling system like a Chevy block. Those blocks are a little more expensive and harder to find since they don't seem to be in full production yet.

The Keith Black stuff is twice as expensive and only available in aluminum.