New to NAS, looking for suggestions (music recording)

on my old PC I did a lot of home recording, using Reaper and a few VST licenses through iLok.

I recently upgraded my home PC and went with a totally fresh install. I moved over a single drive from my old PC just for some extra storage, but I'm left with my old PC with a little less than a terabyte of songs, ideas, music sessions, some old masters, and various important/unimportant documents that I'd like to keep, without transferring the hard drives directly into my new PC (I just don't want to do this if there's a better long-term solution.)

So basically, my head says NAS. Ideally I could set up a NAS, either in my basement hardwired into my router, or just hardwired directly into my new desktop, Dump my entire old computer into it, and then access and write directly to it from my new computer if I wanted to mess around with some music stuff.

does it make more sense to:

a.) take the components from my old PC (7800x/2080 and 32 gigs of ddr4) and build a mini itx board, install OS, stick some big hard drives to it, and go from there?

b.) buy off the shelf solution, dump old PC into it, solve for x?