65 Barracuda 1st time GONNA NEED ADVICE

I bought a 74 Duster that has been through a police pursuit that ended in the dusters demise in a grove of trees. I am going to use it to swap my front to disc and 4.5" bolt pattern. It has a 318 (as does my car) and it has headers on it. What are the chances that the headers will fit in my engine compartment? I think the duster has a bit more room to work with, right? May find out or may just keep manifolds. Seems to run pretty good with the manifolds and they are already on there :)