Back in the early '80's, a friend of mine had a '65. Came with the 425, but he swapped in a later 455 from a 98. Other than that, stock except for wider rims and tires, and some Moog Cargo Coils in the back. Doing 100 mph on a nice smooth new section of highway was like sitting in your living room. Leather buckets, console shift, all the gauges, in an 88 body. Following video shows the 64, then the 65.
https://www.youtube.com/watch?v=0woJIaHiWX8