69' Dodge Dart Resto/Upgrade in NY
Welcome aboard!
They are not '69 Dart seats, so you will need to start fabricating to make them fit. I think they are going to sit too high. Those "risers" make them look like they maybe came out of some kind of truck/van?
If the motor is already .060" over, chances are it'll now need sleeves. I was quoted $100/cylinder a few year ago, but prices for that kind of work are all over the place. But it's a big reason why swaps to 360s and 408 stroker "crate" engines are so popular these days. Unless its a numbers-matching car, having a '340' doesn't really matter to most people.