As per the edit on the OP:
decided to turn this into a sort of build log now, maybe more accurately a “thinking out loud” running post. Maybe it will help others who come behind me starting from a similarly low knowledge level to mine, if they stumble across it. Or feel free to participate if you just like conversing about this kind of stuff. I certainly appreciate any input, but I feel like I have a good footing now and don’t want to specifically seek out people’s time.
Discovered a few things that have slowed my thought process, as well as general laziness and wanting to get other things squared away first have put this on the back burner (if anyone can explain enabling hardware encryption on drives that claim to support it, do let me know) so I haven’t actually built anything yet. I have at least improved my data hygiene and collected everything (including stuff I thought was lost, yay!) onto one of the drives, leaving me with 4 available for the first incarnation of the NAS. I think I’m good with 54 tb usable for now, and a lower drive count will make expanding slightly easier in the future I think.
Now for the snags. I dug the old hardware out of cold storage and put it together as a stop-gap while my main PC’s boot drive was being RMA’d and good news, it still works (this is how I got that “lost” data back). Confirmed the board has 8 SATA ports, but what I didn’t remember is that half of them are SATA II. Now that probably doesn’t really matter because spinning rust, and I don’t really need this thing to be all that fast anyway, but it’s not great. I also don’t know if mixing sata gens will be a problem for TrueNas. Worse, one of the III ports appears to be dead. Needing 1 port for the boot SSD (going to re-purpose the win7 500gb drive), that leaves 2x sata III and 4x sata II ports available (assuming no others are dead, I haven’t tested them all specifically). Further still, the motherboard doesn’t have video out on it, so I can’t use the IGPU like I was planning and will have to use the old 1070. The power savings from not having a GPU was one of the factors weighing in favor of the 2600k build. That said, pretty sure the 1070 idles quite low, so not a huge deal. The bigger problem is that takes away one of my precious PCIe slots, further hurting the prospect of future expansion under this config.
This all pushes me closer to the “just go ahead and upgrade, then use 5600x system for NAS” plan. Pushing back against THAT thought is the “zen 5 will be here soon*TM” thought. So I think where I’m landing is I’m gonna go ahead on the 2600k despite the drawbacks until I decide to bite the bullet and upgrade the gaming PC, and if nothing else I’ll be playing around and learning Truenas better. I’m gonna try not to put anything critical/permanent on it so I can just nuke it and start over if need be rather than fumblef**ing my way through upgrading the system without destroying the data.
Fully aware as I say this that nothing is as permanent as a temporary solution. Going on 2nd month of that “temporary” rebuild while I figure out how I want it “permanently” and have added almost everything back I told myself not to bother with because it’s gonna be wiped anyway.
Further musings for a future post since this one has gone on quite long enough are physical 3.5" slots, best way to add SATA ports, and how I want the data pool set up with maybe adding fancier stuff like metadata/SLOG on SSD.