I'm not an expert but I did stay at Holiday Inn Express....
My understanding is that FE engines tend to keep too much
oil up in the top-end. So what most builders do is open up the
oil return passages in the heads. They also can add a restrictor in the passages that bring
oil to the heads. Pretty important stuff if you are running higher RPMs. I don't think the side oiler has this problem...but I'm not sure