Wait until you receive the item. Inspect it to see if it is acceptable.
If it is acceptable, go to Paypal and repay the refund to the same email address.
If it is not refundable, send it back.
Neither you or he can ethically have both the money and the product.
You have 45 days to open an Item Not Received Dispute. You have 60 days to leave feedback. Even more important to the seller than feedback are the Detailed Seller Ratings.