Syscall numbers shouldn't be a problem if you link against ntdll.dll.
So now you're talking about the ntdll.dll ABI instead of the kernel ABI. ntdll.dll is not the kernel.
...isn't that the point of this entire subthread? The kernel itself doesn't provide the stable ABI, userland code that the binary links to does.
So now you're talking about the ntdll.dll ABI instead of the kernel ABI. ntdll.dll is not the kernel.