After DAYS of digging, someone on IRC suggested that I try to use the
Windows 7.1 SDK Command Prompt
Shortcut (links to C:\Windows\System32\cmd.exe /E:ON /V:ON /T:0E /K "C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\SetEnv.cmd"). I think you MUST have the older 7.1 SDK (even on Windows 8.1) because the newer ones use msbuild.exe instead of vcbuild.exe which is what node-gyp wants even though it's twice as old as node at this point :/
Once in that prompt, I had to run the following to get x86 context because the compiler was throwing as error otherwise about architecture:
setenv.cmd /Release /x86
THEN I was able to successfully run npm commands that were trying to use node-gyp to recompile things.