I’m a big fan of EPYC 7000 series right now. There’s alot of good deals to be found as retailers are making room for 9000 series stuff. It’ll still be a few years before its “cheap”, but you can absolutely get a solid EPYC sysem at your price point. You’ll get much better PCI-E connectivity.
I recently rebuilt one of my NASs with a Supermicro H12-SSLI and a 7F52 I got used on eBay a couple years ago. TN-Bench -- An OpenSource Community TrueNAS Benchmarking and Testing Utility - #23 by NickF1227
I’d also recommend more, smaller DIMMs if you can get 16GB ones instead.