[Reeve of shinra]

If I were you, I would:

a) Back up the db just because you never know
b) Try to compare your hacked vb to an unhacked vb303 to see what files YOU have modded.
c) Of those files, see which ones were updated between 3.0.3 and 3.0.7 (listed below are the files that were updated between the two since I also waited).
d) Back up the files you will need to change
e) Re-hack the new vb307 files to add in your edits
f) Upload the new files
g) Run upgrade

Here is a list of the files that were updated between 3.0.3 and 3.0.7

/
announcement.php
attachment.php
calendar.php
cron.php
editpost.php
external.php
faq.php
forumdisplay.php
global.php
image.php
index.php
joinrequests.php
login.php
member.php
memberlist.php
misc.php
moderator.php
newattachment.php
newreply.php
newthread.php
poll.php
postings.php
printthread.php
private.php
profile.php
register.php
search.php
showgroups.php
showpost.php
showthread.php
subscription.php
usercp.php
usernote.php

/admincp/
adminreputation.php
attachment.php
bbcode.php
cronadmin.php
css.php
forum.php
forumpermission.php
image.php
index.php
misc.php
moderator.php
phrase.php
stats.php
subscriptions.php
template.php
thread.php
user.php
usergroup.php
usertools.php

/archive/
global.php
index.php

/clientscript/
vbulletin_editor.js
vbulletin_stdedit.js
vbulletin_templatemgr.js

/includes/
adminfunctions.php
adminfunctions_backup.php
adminfunctions_help.php
adminfunctions_language.php
adminfunctions_options.php
adminfunctions_template.php
adminfunctions_user.php
db_mysql.php
functions.php
functions_bbcodeparse.php
functions_calendar.php
functions_cron.php
functions_databuild.php
functions_editor.php
functions_forumdisplay.php
functions_login.php
functions_newpost.php
functions_online.php
functions_subscriptions.php
functions_wysiwyg.php
functions_xml.php
init.php
modfunctions.php
sessions.php
vbulletin_credits.php

/modcp/
deletedposts.php
index.php
moderate.php
user.php

/subscriptions/
authorize.php