2016 peterbilt 579

[65transport]

Looking at purchasing a peterbilt 579 with 660k miles and has an isx15 motor. It’s specced out how I want it (listing says 600hp 18spd 270”wb disc brakes air ride front) but it hasn’t been overhauled and sounds like it hasn’t needed much motor work aside from a recent head gasket.. What are some things I should be concerned about or questions to ask the seller. He wants 65k for it and that seems high for that many miles.

Thanks!