I think its a great idea to switch to a synthetic oil, if for no other reason to be able to go longer between changes. However, I'd suggest skipping the Royal Purple. UOA's (used oil analysis) have shown that Royal Purple has a tendency to quickly shear to a lower weight (ex. 5w-30 to a 5w-20), which is not a situation you would want to be in. I would suggest that you consider Mobil 1, Pennzoil Platinum, or Amsoil and stick with the Motorcraft FL820s oil filter. The Motorcraft oil filter has the Ford preferred location of the bypass valve (threaded base of the filter), most others (Wix, Mobil 1, Pure One, etc.) do not.
I personally use Mobil 1 5w-30 (available at Walmart in a 5QT jug for $21), and a Motorcraft filter (also at Walmart for about $3.50). I run the oil, and filter, for 5000 miles.
I don't know how many miles you have on your truck (my 01 has 81,000), or how well you kept up on oil changes, but I would also suggest that you consider an Auto Rx treatment before the switch. If you do that, you will remove any sludge or varnish that may have occurred, and start over with a squeaky-clean engine.
Harvest Gold 2001 Ford Ranger XLT 4x4, Off Road package, SOHC 4.0 automatic, Line-X bed liner and step rails, Silverstar bulbs, Alpine CDA-7894, Alpine R series 6.5 components [front], Alpine R series 5x7's [rear], "hard wired" Passport 7500s radar detector, 35% tint on sides and top of windshield, Undercover tonneau, Rancho RSX shocks, Clifford Matrix RS2 remote remote start/alarm, BF Goodrich All Terrain T/A ko tires, blinker mod, Fusion'd grille, 06 emblems, clear corners, Wet Okole seat covers