If you did not mention it you ought to give Fuel Injection Pump timing a try. White smoke can be atomized unburned fuel do to Fuel Injection Pump trimming not being advanced enough (late timing).

I had this happen when I installed a Fuel Injection Pump wrong. I got billowy clouds of pure white smoke coming out of the tail pipe.
When I did the timing correctly that white smoke disappeared.

What about the Camshaft timing? Look up the 2mm Method

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84 300D, 82 Volvo 244Gl Diesel