- Check your PCV valve and replace it necessary
- At idle, remove (and block) PCV valve and oil cap, observe if there is significant smoking from those holes. Rev engine, and check again.
- Check your compression on each cylinder. If compression is low, squirt in some oil, and check again. If that temporarily boosts compression at crank speeds, it's a good sign that your rings are shot.
- check your coolant for signs of oil, and vice versa. That's potentially a 40yr old head.
Do you know the full history of the car?
If a 40yr old has genuinely done only 91kk, that probably means that its spent a lot of it's life sitting. Unfortunately the bores start to corrode after sitting idle for too long, and then get cleaned next time it's run. Repeat that process over 40 years, and they could be extremely worn.
Heavy Blue smoke under acceleration is generally a sign of oil getting past the rings.
If, with all other factors being equal, the smoke on takeoff is proportionately worse relative to the length of time idling at the lights, that can be a sign that oil may be getting sucked into the intake.