Yes, avoid epoxy. Appropriate cement only. For longevity and reliability, you want it to chemically fuse into a single piece (essentially, chemical welding), not two pieces with an adhesive layer between them.

Also, Steve is correct that depending on your situation a metal piece might be an easier solution. I'm using some spare universal intercooler pipes and silicone elbows as a temporary crossover pipe until I get the Rotrex back on the car. Welded on a bung(s) for IAT sensor, crank case breather, and idle air. Consider wrapping it with some sort of thermal barrier though as the radiator will want to heat it up.