Yep. That's the root of the problem.

AS built their win64 build with "Microsoft ® Windows Server® 2003 R2 Platform SDK", but that has been superseded by "Windows SDK for Windows Server 2008 and .NET Framework 3.5", and all pages for the former now link to the latter. And as you can never get a direct link that works for more than a day or so, it effectively makes it impossible to obtain the same compiler as AS used.

I've succeeded(*) in hacking my way past that problem by creating a dummy bufferoverflowU.lib that exports a single static int call dummy. By placing that the appropriate place, the build completes.

However, whilst the build succeed, I'm getting a runtime error R6034 when it tries to load the resultant dll. This is a problem that's come up here before (I think I may even have been the one that tracked down a solution to it?), but I cannot make it work for x64.