Pack now or haul later. GFO has the best reputation, carbon fiber and PTFE. Controlled thermal expansion and teflon lubrication. The old flax turns to concrete under heat and pressure and has a higher drip rate compared to the GFO. The article you have linked is a classic, just wished that my stuffing box was as pristine and easy to reach.
If you are brave, toliet seal wax can be packed into the gap at the shaft(outside if you dive on it) that can slow the leakage down to a drip to facilitate an in water change out. This is more risky and if you find any complications, you may still nead to haul.