You need to put your headers or manifolds on the engine, put on what ever oil pan you intend to use. You need to mount your radiator and have the water pump and fan on your engine. You will put the engine where it needs to be to fit in the car. You need the steering column in and see where it will go to hook to the Dakota rack. The engine will probably set back quite a bit from where the Dakota mounts are. Level the engine from side to side, then get it close to level from front to rear using the carb surface on the intake. That way your float level will be correct when setting on level ground. I used the cradle mount brackets from an '85 5th Avenue, but widening the Dakota brackets will work. I would install the cradle mounts on the engine, then bolt on the brackets and weld them to the frame wherever they need to be. You will probably need to make some sort of gussets to connect the brackets to the frame. Then make your transmission crossmember and weld it where it needs to be. I am doing the same thing now, I am putting a 360 in a '38 Plymouth, I have the '38 sitting on a complete '89 Dakota chassis. The wheelbase and width of the Dakota are perfect for the '38.