How do you tell what liter your Slant 6 is?

Thanks for the advice, I decided to take it to a shop and have a professional do it. I do not want to make the situation worse. Sorry to hear about 383 wedge, from hearing your story I have extremely bad luck so I did not want to chance it. There gonna drill it our for me tomarrow. Also gonna run some compression test to make sure fireing properly since this vehicle is gonna be my new daily driver. Thanks again for your help.