Align the oil pump gear flats with the flats of the crankshaft
Feuling recommends assembling the cam plate, oil pump, cam shaft etc together on the bench, lining up the oil pump gear flats with crankshaft flats and installing the complete assembly into the cam chest as one complete unit
Twin Cam engines: rotate the crankshaft flats so they are horizontal and align oil pump gear flats horizontal to match
M8 engines: rotate the crankshaft flats so they are vertical and align oil pump gear flats vertical to match
This procedure has proven to provide the best seal on the back scavenge port of the oil pump to engine case as the parts are always going inwards towards the scavenge port