A little off topic, but what 'globals_on' issue are you referring to? The reason I ask is that I use PHP 4.3.2 and GoLive and I haven't had any issues at all.
As far as reverting back to 4.2. Use Pacifist or some other utility that can read the pkg files and just extract the 4.2 module. The apache modules are located in /usr/libexec/httpd.
Also, how did you install 4.3? Did you roll-your-own or did you use the package from entropy.ch?