Wordpress & Git, urgent permissions issues, need help...

Heya,
So I recently upgraded my MacBook to a solid state drive, during the re-install of Snow Leopard I chose to abandon MAMP and use the built in Apache & PHP and in doing so moved my ~/Sites to /Library/WebServer/Documents from a Time Machine backup. During this transition the permissions were changed (I expected that but didn't change them directly).
All of the sudden Wordpress couldn't write to various places such as .htaccess, wp-content/uploads, wp-content/plugins, etc... So I changed the user and group to _www:_www correcting that issue, but then Git couldn't write to it's own directory.

 At this point my permissions are spencerhill:staff 755 for folders and 644 for all files. And I'm completely confused as to how to untangle everything so it's set it the appropriate default user, group and symbolic privileges preventing me from doing any work. Please help!

 Thank you!