Check the brakes over real well. If you come I-5 you'll want to be sure you can go slow enough coming down that pass!
I haven't driven any of the eastern routes in the last 20 years so I can't comment on them. I have driven 101 several times in the last few years and would NOT choose that route in an old truck.
Back in the 80's I made a couple of moves in a '51 GMC. I bought it one week and drove it 300 miles the next. The brakes were fine, but the pressure line to the oil filter broke and emptied my crankcase. It was dark and I had no dash lights (dumb!) so I didn't know until it started knocking.
I made it the last few miles, but it was noisy. Six months later I replaced one rod bearing and then used it again to move 100 miles.
I sold that truck to pay for an engagement ring. I still have the girl and don't regret her, but I do regret selling that truck.