Yes as long as you can prove you sent it and prove it through tracking you should in all aspects win the dispute and they will reverse the chargeback. Unfortunately Paypal seller protection is a joke. Just pray they work on your side as with something as UNRELIABLE as paypal seller protection. You might end up loosing money in the end.
Paypal works for the buyer not the seller. Even the dispute process is a complete joke. Once a buyer turns a dispute into a claim . You only have 2 options. Refund or tracking number. You have no say or no way to put your word into this matter. But the buyer can say and do pretty much anything they want.