Tom,
I just looked at my spare adapter block. It matches your block. I think the sleeve is positioned in that manner by design. First, without being able to measure the port slot in the sleeve, it seems the bypass valve(BP)port has a larger area than the exit port out of the cooler adapter block behind the bypass valve. Additionally, the floor of the cooler's return port is relieved to a lower level than the slot in the BP valve which should facilitate oil flow into and through the bypass valve. If you'll check the oil exit port leading into the filter base, you can see the lower edge of the BP valve's slot is almost perfectly aligned with the floor of the oil exit port. If rotated into better alignment for the entrance into the BP valve, then the exit from the BP valve will become obstructed to some degree. Finally, the angled orientation of the BP valve should help provide a longer, smoother transition for oil flow through the cooler adapter block into the filter base - instead of having the oil flow in and crash into a small diameter 90* flow changing port.