open task manager and "end task" all installer and installer 32 that are the lowest ram and cpu usage. keep at least one open each usually does the trick. I used to "end task" one at a time and then check the status of the install until it completed. PITA! but works, haven't had that problem since installing Windows Updates prior to installing Office though.
I have noticed that when Office installation doesn't go beyond 80% mark for 30 minutes, CPU usage would be zero(and would stay zero too), memory usage would be minimal and not changing at all, even hard drive activity would be zero or minimal too. Infact, installation reaches to 80% mark in first 2 to 3 minutes or so... and then every activity becomes either zero or minimal.
been having issue across many systems since the first release of Win8 before Win8.1. Same thing with install every time. Glad you got it going