Thank you all for the replies! All good stuff.
In my searching, I have seen those Centramatic wheel balancing rings with beads. They even have them in our common 10 x 7.25 bolt pattern. They sell them for the P30 chassis:
Centramatic Balancing for the P30Even though this truck project of mine will see long cross-country journeys, I will not be putting that many miles on it over the next 15 or so years.
Still, balancing the tires in some way is on the to-do list. No point in ruining a $2,000/$2,500 set of tires because of imbalance/unbalance. Might have used the wrong word there...
David