I've put oil straight from the pan into my tank before. I'd recommend at least filtering it through a 5 micron sock filter before dumping it into the tank, but there have been times I've done an oil change on the road and just poured it into the tank. 7.3's are pretty tolerant for WMO in my experience.
How much filtration you want to get into all depends on how much WMO you plan on burning. If you want to run extensively on WMO, then a centrifuge is in order. If its just 4 gallons of oil every 4500 miles then a $5 sock filter will suffice.
Personally, I won't burn anything that hasn't come out of an engine I own. Too many people using the same drain pan for coolant and oil, and I don't want to go through the hassle of de-watering and filtering their crap.