Scrap or fix head gasket

Hello Chevy fam. I have a 2016 Chevy Sonic ltz turbo 1.4 with only 104,000 miles on it located near Sacramento CA. It's throwing codes p0300 and p0118/ giving signs of a blown head gasket. I have a friend's friend who I've never met and isn't a certified mechanic who said he would fix it if I buy parts and pay him $350. That sounds too good to be true so I scared myself out of it. The car is in my friends driveway and isn't registered. My friend needs me to move it ASAP. It's in beautiful shape if the head gasket wasn't blown. It would be worth $6000-$7000 if it didn't have issues. How much can I sell it for as is and what is the best way to sell it quickly for the most money? Thank you in advance!