I think you have it right. Heres the lubrication diagram.
Oil pump supply (delivery pump): rear side fitting on motor to bottom of tank.
Oil pump return (scavenge pump): front side fitting on motor to top of tank.
Small vent line: top of tank to rear of motor.
You might consider running an oil pressure gauge, at least until this is sorted.
I wouldn't be downsizing the oil lines too much, and make sure you choose oil resistant hose.