The single overhead cam engines (SOHC) are non interference but the DOHC Dual overhead are interference. So only the DOHC will damage the valves.
That price sounds high as the book time is only 1.8 hours. So that means if they charge $100 per hour it it still less than $200.00 in labor and the parts are less then $200.00. So even if they mark this up 10% that still puts it around $500. Clearly this is going to change if they charge more per hour but I doubt they charge $500.00 per hour.
Sounds like they are not sure how to do it and so they are charging more then they need just because they either don't know or don't want to do it. So if you are going to have them do it then it is going to be worth their while.
Lastly it sounds like they just gave you a ballpark over the phone because not many shops give estimates that range $500.00's.
Please run through this info and let us know if you have other questions.
Images (Click to make bigger)
Tuesday, August 17th, 2021 AT 4:12 PM