Outside access to Epicor Portal Issue

We have our sharepoint site on a port number that we gave access through our firewall and using AD to log on to the site. Works beautifully. Except that overlooked one thing, even though the web parts for the views from Epicor Portal work great when you try to save the view as any file, try to drill down, or update... it calls the epicor portal scripts that are on the Epicor Portal end. The Epicor Portal is installed on Port 80 as per the standard install, while my sharepoint is installed on a random port number I choose. I have a hole in the firewall to allow the port and mapped to the public with that port to make my sharepoint work. Now does anyone know if I'm going to have to allow another port access through the firewall and map the Epicor Portal to that port? And am I going to have to allow 80 open, I really do not want to let 80 open through the firewall.