Those permissions will work. If you're feeling paranoid (and you have other users) you might want to use 700 (directories) and 600 (files) on stuff that has private data like passwords and the actual mail-bodies.
The profile layout is a little bit different from one OS to the other. Windows does this:
Code:
Application Data
Thunderbird
profiles.ini
registry.data
Profiles
i5ewvyde.default
whereas my Debian has this:
Code:
.mozilla-thunderbird
appreg
profiles.ini
i5ewvyde.default