I just rebuilt the Dana 60 axle in the front of our cruiser. Different axle but it goes together exactly the same way the Toyota axle does. The bearings on both sides were bone dry and had locked up the bearings letting them spin on the spindles thus wearing them pretty badly. I replaced both spindles because the inner bearing race needs to fit snug on the spindle to prevent the inner race from spinning.
On the Dana 60, after installing new bearings and races, you use a torque wrench and tighten the inner bearing adjustment nut to 50 ft lbs, spin the hub several times, then back the nut off 1/8 to 1/4 turn until the preload is about 6-7 on the fish scale.
Unless you crush the needle bearings into the race by massive over torquing, I can't imagine that causing the inner race to spin on the spindle as long as you back it off to the appropriate pre-load.
Did you buy OEM bearings or after market? I've seen some after market bearings where the tolerances are looser where they fit to the spindles. Or your original spindles may just be worn enough that you need to replace them.
Randy Rosetta KDØKWX TLCA #19351 NOW 2015 Rubicon Hard Rock & (2) 1970 Boss 302 Mustang's THEN 69 FJ40 Buggy "Meanie", Mini-truck "Gecko" & 74 FJ40 "Blue Mule"