This is what you want. http://www.mediafire.com/file/zwfozydgq8a5bci/OldDays_1.6.4.zip/file

Yes, it's for release 1.6.4. How it works is it includes every single feature from alpha/beta even including the old loading screen/menu, literally EVERYTHING, sounds textures features etc all togglable from a menu. You can play beta minecraft but with new generation from 1.6. You can play alpha with beta generation but with new features from release 1.6. Or whatever combo you want, and of course you can play 100% vanilla beta 1.7.3 if you wish.

What you will want to do, create a preset under beta 1.7.3 (or alpha) and then change the terrain when you create a new world to what you want.

Here is the preset I use, plus an installation guide: https://www.reddit.com/r/GoldenAgeMinecraft/comments/cwsxpa/beta_173_preset_download_old_days_mod_followup/