Resurrecting Visual C++ 9.0 application - c++

Question

I've been handed an ancient C++ application and asked to see if I can get it building and running again. I first tried building it using Visual Studio 2022 and ran into a lot of problems, so thought I would try building it in the environment it was used to.
The VCPROJ starts with this:
<VisualStudioProject
ProjectType="Visual C++"
Version="9.00"
Name="FsxApp"
ProjectGUID="{D0B8B3A6-3037-46F2-93D2-40318F591EEE}"
RootNamespace="FsxApp"
Keyword="MFCProj"
TargetFrameworkVersion="131072"
>
Looking up Visual C++ 9.0 in wikipedia, it says that version maps to "Visual Studio 2008 9.0" so I installed Visual Studio 2008. For some reason, Visual Studio can't find the files that are right in front of it so I had to add $(ProjectDir) to the "Additional Include Directories".
Now, VS complains because it can't find afxwin.h so I added the path of my modern MFC folder, and then it couldn't find winsdkver.h and winapifamily.h, and I found those in subfolders of a folder titled "Windows Kits" that I added to the list.
And now it's complaining because
#if (WINVER < 0x0501)
#error MFC does not support WINVER less than 0x0501. Please change the definition of WINVER in your project properties or precompiled header.
#endif
and sure enough, my stdafx.h says
#ifndef WINVER // Allow use of features specific to Windows 95 and Windows NT 4 or later.
#define WINVER 0x0500 // Windows 2000 or later. (Necessary to use GetTitleBarInfo())
#endif
#ifndef _WIN32_WINNT // Allow use of features specific to Windows NT 4 or later.
#define _WIN32_WINNT 0x0500 // Windows 2000 or later.
#endif
#ifndef _WIN32_WINDOWS // Allow use of features specific to Windows 98 or later.
#define _WIN32_WINDOWS 0x0500 // Windows 2000 or later.
#endif
and if I change all of those to 0x0501, it is very unhappy:
winnt.h(7063) : warning C4163: '_InterlockedExchangeAdd8' : not available as an intrinsic function
winnt.h(7349) : warning C4163: '__cpuidex' : not available as an intrinsic function
atltrace.h(92) : error C2065: 'nullptr' : undeclared identifier
atlwinverapi.h(714) : error C2159: more than one storage class specified
atlwinverapi.h(714) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
atlwinverapi.h(714) : error C2440: 'initializing' : cannot convert from 'PFNLCMAPSTRINGEX' to 'volatile int'
atlwinverapi.h(714) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
atlwinverapi.h(714) : error C2440: 'initializing' : cannot convert from 'PFNLCMAPSTRINGEX' to 'int'
atlwinverapi.h(714) : error C2446: '==' : no conversion from 'PFNLCMAPSTRINGEX' to 'int'
atlwinverapi.h(714) : error C2040: '==' : 'int' differs in levels of indirection from 'PFNLCMAPSTRINGEX'
atlwinverapi.h(714) : error C2440: '=' : cannot convert from 'PFNLCMAPSTRINGEX' to 'int'
atlwinverapi.h(714) : error C2440: '=' : cannot convert from 'PFNLCMAPSTRINGEX' to 'volatile int'
atlwinverapi.h(714) : error C2440: '=' : cannot convert from 'PFNLCMAPSTRINGEX' to 'int'
atlwinverapi.h(714) : error C2446: '!=' : no conversion from 'PFNLCMAPSTRINGEX' to 'int'
atlwinverapi.h(714) : error C2040: '!=' : 'int' differs in levels of indirection from 'PFNLCMAPSTRINGEX'
atlwinverapi.h(716) : error C2100: illegal indirection
atlwinverapi.h(716) : error C2064: term does not evaluate to a function taking 9 arguments
atlcore.h(37) : fatal error C1083: Cannot open include file: 'type_traits': No such file or directory
which isn't surprising at all, when one grabs random include folders.
So then I wondered if I could find the correct version of MFC. According to wikipedia, the MFC in use during Visual Studio 2008 was mfc90.dll but if you google "download mfc90.dll" you get a bunch of questionable links, and those that look semi-possible just have the DLLS, not the H files.
Is finding an old version of MFC my best bet? Is there some other way to get an old application building?