You seem like you have an actual use for a high number of threads but if you want dissuading:

AMD are just about to launch 7nm versions of all their current lineup.
Investing in a large single SATA drive when the proposed system has so many PCIe lanes seems a bit bizarre, it won't even saturate a 10Gb network link.

What really stands out is you're jumping from a dated consumer quad core to massively scaled, modern enterprise system. Per thread performance on the Core2 was beasted back when Sandy Bridge came out in 2011. Literally any of AMDs non-budget offerings will be a big upgrade. I'm not saying you should cheap out totally but consider that just the standard Ryzen consumer chips are going to be at least twice the cores, much better IPC and even though it's just two RAM channels, they're offering around 3x bandwidth on what you currently have.

To me processing would be done by your main rig, not server. My idea of a server is extreme low power, fast(very,) reliable, spacious.

cheap used infiniband fdr 4x cards and cable that do 6.82GB/s, cpu performance irrelevant in the transfer, processing handled by the cards.
old system that uses vastly cheaper ddr3 ram, 128/256gb using 32/64gb dimms, caches drives, 90+ hit ratio, nearly always operating out of ram, it's slow for memory nowdays, but still far faster than disk in bandwidth and as always latency. Oh yeah, infiniband is extreme low latency too, so that aspect is retained.
modded to low power(10w idle) https://ssj3gohan.tweakblogs.net/blog/8217/fl … p-computer.html
1/2 tb ssd most frequent cache miss still relatively fast, ssd can be setup to cache or as tiered storage(faster, more space)
8tb hd (not raid, just one drive, security of data is handled by having backups, I gain more from power savings than 24/7 uninterrupted uptime for personal use, why I would also pay the premium to a point for a larger drive than array of the cheapest drives) online/on call data space
ups for brown outs.
offline backup: array of cheapest used 3tb sas drives(current price space sweet spot) that are only powered up and used for weekly/monthly backups, could be dedicated system for backups, power down configuration, usb, whatever as long as no power draw when not in use and its only used for backups.
low power file server allows for 24/7 without killing the power bill.

main rig, diskless, network boots off 6.82GB/s file server.

I'm all about having the right tool for the job. I have three Supermicro boards in 1U rack enclosures. One is a low-power Atom that hosts my NAS (software RAID-5), another of the same model for my router / firewall, and a third multi-core board with a bunch of RAM for a VM host.

One big reason to have these separated is, if I lose one or it's just time for a rebuild, I don't lose all the services all at once. In a pinch I can even have the VM host take over temporarily as the router, so I can stay online while I'm rebuilding it. Having all your eggs in one basket makes for stressful maintenance.

Could add a nearline storage layer, how I would handle the large array dosfreak already has. Working set fitting in cache and ssd and roaming set venturing into the 8tb drive of the setup I mentioned, and then a powered down large array for the rare access. dosfreak could probably save on some power given he probably doesn't constantly touch all 11x 12tb on the regular, pull out a drive, or two for a smaller raid if you must, leaving the larger array for the infrequent access, the drive/array size configurations conforming to your particular usage pattern.