I would love to see a 60 year old smoke tree! I bet it is gorgeous!
Smoke tree blooms on it's new wood, which is why, since it blooms in the spring to early summer, it should be pruned right after it has bloomed. This way you get the whole rest of the season for new growth for it to bloom on next spring.
If this doesn't matter to you (whether you get alot of blooms or not) then go ahead and prune.
One of the most important parts of pruning is to keep injured, diseased, or dead wood out of the tree.
Remove all crowded stems and weak growth, and any branches that actually cross each other.
Always cut stem stubs close to a main stem to permit healing. There should not be a stub left long enough to hang your hat on, or you are inviting disease.
Nip tips of new growth to increase bushiness.
Removal of sucker growth on trees is essential to prevent diversion of growth in the wrong area.
Natural pruning gives plants an opportunity to grow in their own form. Hedge-sheared plants are robbed of their individuality, flowers and natural beauty.
Better plant shape and regrowth is developed when plants are pruned gradually over a period of time in contrast to once a year heavy pruning.
It is never too late to correct past pruning errors. Plants have great ability to recover from poor pruning practices and again perform normally.
Hope all of this helps and good luck!