Firstly, make sure you report the damage to FedEx and get a refund ticket in. I've won battles with UPS for items that weren't even insured, you just have to be persistent.
For most of my plastic-to-plastic bonding work, I use SciGrip/IPS Weld-On products. They make a ton of different formulations for different applications. For my acrylic applications, it's a exothermic reaction when you mix the two components that actually solvent-bonds the materials together into one piece. A bond like that may be critical for a component that will see long-term vibrations.
Here is their bonding selection chart (what-to-what material with the suggested Weld-On product number in the cell):
https://www.acplasticsinc.com/media/documents/Adhesive_IPS_Weldon_Selection_Guide.pdf
If you got this route, you'll want to make sure that the gasket channel is still clear. Most of the two-part formulations have a pretty high viscosity with little squeeze-out as long as you don't overload the joint.
It also depends if you were trying to get the porting job tier from AFS where he disassembles the Cobra Jet intake. I don't know when the best time would be to make the repair if it's coming apart anyways for the porting job. EDIT: Like Fabman said, since Bret does have a service where he cuts these apart for full port race clients, he is probably in a good position to make the repair as long as you communicate the need up front. I thought that perhaps this was on the return trip post-porting. He did some custom work for me and it was both readily accepted and fairly priced.