You have options now. You can flash the fastboot files via RSD Lite which will take you back to 744 and from there you can OTA to 748 then to 173. The beauty of this method is that you keep your setup (no factory wipe required).
Or you can download the RAZR utility which looks pretty good. I downloaded the lite version to check it out and it's as simple to use as people say. The advantage of this method is that you can get to stock 173 but you will lose everything because this method will wipe the internal memory.
Are your Motorola drivers up to date? It's totally worth it to check because those options are the cleanest and fastest ways to update/revert the phone.
I think that it was in the xda forum where I read that the zipped update files contain all of the apk's. So if you have a lot of time to waste, you can go into the zip file and look for it and then dump it into the directory.
You copy the files to SD and then move using root browser to system/app, change permission for each file you put there to "rw--r--r", that is:
Owner: read, write
Hope this helps, lemme know