Sparky,
Preloading tapered roller bearings (Timkens)is a very touchy proceedure and it is better to be to lose than to tight. The best way (in my opinion) is to calculate or measure the distance between the inter bearing races and then make a solid spacer to fit between the two races that is that dimension, this allows you to tighten the spindle nut as tight as you can make it because the bearing spacing (pre-load) is set by the spacer. I usually come up with the exact dimension then make the spacer in two parts one about 1/4 inch short and then make a series of .245 to .255 thick spacers in .0005 increments and then fit the bearings and spacers till the pre-load is correct when I really torque down the spindle nut. Doing it this way make is easy to always have the correct bearing spacing every time you take the hub off.
If you are having your spindles made have the threads for the nut made to the bearing manufacture's specifications for bearing lock nuts, this will require that there be a keyway thru the threads but then you can use the standard bearing lock nut and washer which give you an almost infinate amount of position adjustments for the lock nut.
Rex