led-panzer's 1984 300D 4-speed
led-panzer's 1984 300D 4-speed
The factor you are not considering here (if I haven't missed anything) is the EGT. Stock EGT is way below the maximum power output. To get up there where you have the sweet spot the car is gonna smoke quite bad. So this smokeless thoughts will go down the drain.
Even the new diesels smoke when giving full power. Like the BMW 335d and 535d. Not as stock but stock they are just that. Stock... That's not even close to maximum power.