For all intents and purposes, there's really no discernable difference in those cpus, only in benchmarks.
Any new platform will be using DDR4, so your old ram is no good, there's really nothing but the case and possibly storage that'll be salvageable.
The 2nd Gen Ryzen will require a bios update on anything older than a x470 motherboard, unless you get lucky and get a mobo made after the release of the cpu. This can be a pain, you'd need a 1st gen Ryzen installed to update the bios, doable just a pain.
To enable OC on Intel 8K series cpu, you need an intel based Z370. Otherwise, you will not have OC options, might as well save a few more $ and run an i5-8400.
Much of what you plan will depend on your budget.