I once owned a 61 Model 122S with a B16 that did the same thing....my first Volvo 44 years ago.
The engine always ran great and then one day it began to produce blue smoke.
Have you recently changed the weight or brand of motor oil that you use?

My problem turned out to be worn oil rings.
I don't know how many miles the car had, but at the ripe old age of 18, I remember running the little engine hard and with various cheap qualities of motor oil, so I learned way back what not to do.

The compression looks OK if maybe a little low, and you removed one possible blue smoke problem by replacing the valve stem seals, so I would guess a ring job is in the future.

hope this helps
steve