Need help assembling top ports of a UHV chamber

I am designing one of my lab's chambers on solidworks. It's a TBNX Chamber and it's shown in the following pictures:

So far I have constructed the base of the chamber along with all the ports except the top ports that are at an angle:

I attempted to find the focal point of the top ports and then go into one of the parts and create a hole in the top plane that would create the hole at an angle as shown in the following picture:

I created a custom flange to attach to the hole and create the port:

The only issue I have is that I don't know how to mate the flange so that it will fit at the correct angle. I tried mating to the front plane like I did with the original hole but it didn't work out and the angle was off. Since I used the revolve feature I can't directly mate to the curved surface.

I'm using Solidworks 2005 and can't figure out any other way to mate the flange so it'll be similar to the actual UHV chamber. Any help will be greatly appreciated. Thank you!