check out www.fsreloading.com they have by far the cheapest prices on Lee loading equipment and accessories. If the cases were not originally fired from your gun they will need to be full length sized then after firing in your gun you can skip the full length size and just size the necks. When sizing the necks no case lube needed when doing full length sizing lube will be needed or youll get your cases stuck.
If the cases are previously used check to see if they freely chamber in your rifle. If they do, reload them and fireform the cases, no need to full length resize them. If perchance they do not freely chamber in your bolt action rifle then yes they will need to be full length resized.
For a 270 wsm I seriously doubt you will have any problem.