Always replace the seals when re-packing.
Bearings can last for several hundreds of thousands of miles if repacked every 90-100k and resealed to keep them clean.
If there is any question on their condition, replace them. Who wants to do this job again anytime soon?
Diesel fuel works great for soaking the bearings clean.
(I actually use heating oil from my oil tank, which is almost the same minus a few additives)
I use spray brake cleaner to finish up the races,insides of the hub, and spindle.
Getting the right torque on the retainer nut can be tricky.
The right special tools are great for this.
I have done so many at this point, that I now just do it by feel.
You are trying for a balance of no drag, and just the slightest hint of play. Once the wheel is back on, you can see how you did by grasping the tire at 12:00 and 6:00, and rocking it inwards and outwards.
Best of luck
1986 300E 5-Speed 240k mi.