PyGTK all-in-one appears to be 32 bit only, so I am stumped other than setting up a separate 32 bit machine just for CHIRP dev. Your instructions say 64 bit users can just download all 64 bit or all 32 bit parts.
There are other ways to get the dependencies in 64-bit form, like getting all the bits and pieces individually, and/or compiling them yourself. They have to match, and reports seem to be pretty clear that 64-bit versions of all of those work fine on Windows, yes.
Is that confirmed? 32 doesn't seem to work under Win7/64 and 64 bit parts are apparently not all available.
Does the .exe build of chirp work for you? If so, then those 32-bit parts work just fine on 64-bit Windows. That installer just lays down a special copy of the 32-bit Python environment that is on my build system.
In the google hits, I see mention of folks tweaking DLL names, and locations (for some reason I don't understand). Have you tried any of that?
I should have access to a 64-bit windows environment tonight and will try to replicate all of this there. However, as I say, the build runs, so the environment (if properly installed) should run.