There's no need for me or anyone to agree, just play a bit
Sure you can try that string, or also try the default fake for FF UA, the first entry in the UA-menu:
Tools > User Agent > Firefox 3.5
I see that google support page says they accect FF
3.6 that would be equivalent to KM1.7 (alpha), not KM1.6, or do I confuse that again??
Anyway, if the other strings don't work, try a FF3.6 string, tons can be found here as examples:
http://www.useragentstring.com/pages/Firefox/
Just a random pick:
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
If that still doesn't work, KM1.7alpha could be tested, but I don't suppose it's that complicated