Simple. Run a short hose from the power beyond sleeve to the inlet port of valve number 2. A power beyond sleeve in valve 2 and a hose from there back into the block under the seat. Then you tee the sump return lines together and go back into the tractor.
One think that hasn't been mentioned yet about using the aluminum block. If and when you need to remove the loader, you will need to consider how you're going to go about dealing with the hoses. If the loader valve is mounted on the loader itself it will need to go with the loader, so you will need to disconnect the three lines and couple two of them together before you can start the tractor. If it's mounted on a bracket that can stay with the tractor you will need to disconnect lines from loader valve to cylinders. Some people never remove the loader except for major tractor repairs.