Hey John, 
  
What about labor? My thinking is swaping the stub axles is a lot of work.  If the bearings are good in the stubs of the 280z, why not? Strut tube thickness aside, isn't the only difference the top hat height? I think stock 280z springs may be a little longer too, but don't recall? 
  
OP didn't state his plans, coil overs, etc., so not sure.