whats the thought process for wanting to move the drain line to the intake side....
would just like to add that a doubt very much that the lines from the head to the sump are actually oil drain unless u have severe problems with ur head filling with oil. This is usually rectified by oil restrictors.
I have lines running from the back of my head to the sump and i beleive its used more as a crank case pressure releif through those lines, into the head and out the breathers that i now have plumbed into a catch can that vents to atmosphere.
By relieving the pressure in your crank case this will allow oil to drain quicker down through the galleries.
also as the engine spins clockwise i would have thought the vacuum (if any) would be from the exhasut side
just my take on it, happy to hear any opinions or constructive critisism