where to buy small block to slant adapter?

this wouldn't be going into an A body, I have a dodge dakota that already has an A-500 (same as 904 but overdrive) and the engine is gone, its 3.9 v6 and I already have a v8 dakota so I figure I would go /6 with this one for a neat factor

doesn't need to be fast or win races or put down record fuel economy numbers, just want something different

I have two /6's and one that was given to me tonight thats completly rebuilt to make a third

Will there be enough length under the hood to move the mounts forward for the adapter and for the /6 engine to fit?