Can't build project referencing self-built FCS and FSharp.Core package

I'm trying to upgrade FCS in the Rider plugin. However, there are issues with building.

Due to https://github.com/dotnet/fsharp/pull/17698 FSharp.Core is no longer referenced as a package, and is referenced as a project instead. We build FCS ourselves but I don't know a way to build FSharp.Core properly, so its assembly strong name matches the one published by Microsoft. Is there something that I miss and it's possible? If not, then we need to find a way to use FSharp.Core package when building FCS.

As a workaround I've tried to use both 8.0.400 and the current preview FSharp.Core versions, but I'm getting an error during build:
```
Error CS0115 :
'FsShim.OpenFileForReadShim(string, FSharpOption, FSharpOption)':
no suitable method found to override
```

It seems there may be some issue in the code generated by F# compiler?
Here's a minimized repro:
[FcsFileSystemShimOverride.zip](https://github.com/user-attachments/files/17150129/FcsFileSystemShimOverride.zip)