How to downgrade Safari from 8.0.6 to 8.0.4?
For testing environments I recommend using Parallels or VMware. You could do an install of Yosemite and then only install the updates needed.

I usually create multiple virtual machines by creating a base VM, then copying it, doing a round of updates, then copy that one, then doing another round on the next copy, then repeat that process until I have all of the software versions I am looking for.

Keep in mind that some of the software you may want to use will require a separate license for each virtual machine.