Power Steering rebuild kits

I have a 1968 PS corvette. I am going to rebuild both the ASSIST CYLINDER and CONTROL VALVE. I need rebuild kits for both. It seems every vendor sells them but I think some kits are better than others. Who would you buy from? Thanks

charlie

NAPA

Cyl seal kit #NPS 7140 $8.69
Control valve seals #NPS 7137 $15.99
Control valve ball stud kit #NPS 7215 $39.99