The emails in PowerStore are sent using Universal Email, but if you would like make the changes manually, then you will need to make the changes to the pp_receipt.php which is stored under WA_Universal_Email/Templates folder.
The product options are stored in the cart description ($WA_Store_Cart->DisplayInfo("Description")) and to display the sku you could use:
$WA_Store_Cart->DisplayInfo("SKU");
let me know if you have any other questions.