Reuse ancient motherboard and ram or no?

My small 4 drive NAS needs a new case to house more drives. I built it 10 years ago. Apart from upgrading the 3.5" drives, I think I replaced bad RAM early on and the CMOS battery a month ago. I also put in a new Corsair modular PSU in 2024. I thought the original Seasonic had died, but in fact it was just a dust accumulation problem on the motherboard.

It currently runs the latest SmartOS (zfs mirrors) with no issues. I do plan to change the OS to Debian with SnapRaid + MergerFS. This frees me from having to upgrade full mirrored pairs of disks which have also shot up in price.

Current Specs
Motherboard: Asus H97I-PLUS Mini ITX LGA1150
CPU: Intel Core i5-4690S
RAM: Kingston HyperX Fury 16GB Kit (2x8GB) 1600MHz DDR3 CL10

Replacing the above with the following will cost around $900 AUD. Hard to justify based on the fact the old gear is getting the job done.
Motherboard: MSI PRO Z790-P WIFI ATX LGA1700 (cheaper options but chose this for the Intel 2.5Gbe NIC)
CPU: Intel Core i3-12100 + Cooler
RAM: G.Skill Aegis 5 16 GB (1 x 16 GB) DDR5-6000 CL36

I'm going to hang the spinning rust off a 9300-8i HBA, so I can limp through with the old motherboard even though the extra SATA and M2 ports on the new one would be handy. I can reuse the power supply. All I really need is the bigger case. At some point in the distant future I can see needing a SAS expander card. Once I get there I will need a new (or newer rather than new) motherboard as the old one has only one PCI slot.

The NAS hosts only media so if something goes bang, I can live without it while replacing parts.

Are there other options? Cheaper new parts? 2nd hand? Chinese motherboards for older processors you see from AliExpress? Maybe I could take an option to reuse the RAM? What would you do?