I have a similar noise.
I recently replaced the bearings and re-greased the bottom bracket on this bike - old 70s Centurion. The new bearings are in a Race - rather than loose as they were when I pulled it apart.
Whenever I am applying some force with pedaling i get a couple of clicks and "pops" click click type noises. once a revolution of the pedals usually when the torque is applied from the Right-side (drive side) crank.
Particularly when going up hills etc.
I thought it might be the chainring stack bolts loose and the chainring is shifting with the increases in torque but i don't think so...
it almost sounds like there is some grit int he BB that is causing bad noises.