DNj OP105 and Oil Pump Sprocket Oversize?

DNJ OP 105 OPump and Stock Oil Pump Sprocket Oversize-Sprocket Replacement

Have a new DNJ Oil Pump (OP105) for my 1987 G63b. When I fit the stock Oil Pump Sprocket I have two issues needing advise on.
1) The key flat on the sprocket is only at the lip and does not extend the depth of the sprocket. Looked at new 4G63 sprockets and it does not appear to have a flat inside the inside the bore to engage the shaft. Recommendations? No flat? Then what engages and turns the shaft? Do I need a replacement?

2) the OD of the Oil Pump Shaft and ID of the old Oil Pump Sprocket is a few hundreth off, so much that the sprocket can off center and spin freely without engaging the shaft? What are the tolerances between shaft and ID of the sprocket?

Seems to me both issues rule out using the original Oil Pump Sprocket? Anyone run into DNJ Oil Pump Shaft not being to specs? Is there a DNJ Oil Pump Sprocket? Is is mine just shot and a replacement will mate up with the DNJ Pump Shaft?