This should be an awesome road trip, I'm looking forward to progress reports!
Speaking of Santa Rosa, there is a vintage military tank in a little park on the south side of town, off 54 & 84, that you can check out and go inside of, the hatch is open.
At Holbrook AZ, be sure to check out the wigwam motel, real teepees with a lot of old cars and trucks as props.
Check the weather in flagstaff, it can be brutal in January. If it looks bad, turn south on 54 at Santa Rosa, shoot down to Alamogordo, then over to Los Cruces and take I-10 west. Even if the weather is good, sometimes I go that way if I am heavy loaded, because I-40 has some serious grades (starting at Albuquerque when you are heading west) that are hard on brakes, fuel, and slow going up. 54 is a nice easy drive, and 10 from Los Cruces to Phoenix is too.
Those Ford one tons are notorious for loose rear brake adjustments, putting all the load on the front brakes. Take a few minutes before you hit the road and tighten up the adjusters. You can do it with a bottle jack and you don't need to remove the wheels.
Tork the lug nuts after 100 miles or so. I lost a wheel on a dually on one of our service trucks before because someone swapped a tire and didn't recheck the nuts later.
Put some cardboard over half of the radiator, to help the heater performance, but remember to take it out when you get into warmer territory.
Make sure you have a signed bill of sale if you do not have the truck registered in your name yet. I had a cop problem driving home in a new purchase, and I had the signed title but he still wanted to see the BOS, which I didn't have. 2 hours of BS before they ley me go.
Good luck, have fun!