68 valiant project....440 tapping ticking sound at 2500 rpms and up

Title says it. This is a new engine that was tuned on the dyno. Since getting it in the car i have had this noise. I thought it was an exhaust leak, but now im not sure. If it is it would have to be on the header flange, I've checked everywhere else. I do not hear the sound at idle. It is heard in park and under load. Any thoughts or input would be appreciated. Video below.