Change wordpress port from internal 8000 to external 80

Guys,

I have a wordpress installation that was setup on port 8000, on one of my internal server as port 80 for apache was already being used. So i need to make it available externally with the standard port 80 without changing the internal port. I am using mod proxy or redirect on apache to link my internal server sites to the external domains. It would be great if someone could help me with this setup.

localserver:8000 (internal server) –> blog.example.com (external server)

Thanks is advance.