I only run 2 quarts of fluid in Dana 60 rearends. That's all it needs...street or strip.
Running a spool on the street is not asking for failure of any kind...been doing it for years and never had one problem.

It will turn a little harder w/ the spool, but may just be tight b/c of the new bearings.
Unless they set it up way too tight or the housing is bent like Cab said.