How to upgrade to specific release on Mac OS X (e.g. 10.7.3)?
If you start from a base install - 10.n.0 then you can always directly update to a given 'point release' by using the Combo Updater for that release.

These appear to always remain available from Apple.

The Combo updater for 10.7.3 is at https://support.apple.com/kb/DL1484