Oh crap..... Internally balanced engine with an external balance flex plate?!

Let me do one post before everyone misunderstands what I am saying. The car is full of poly bushings, poly spool mounts, poly trans mount and torque strap.410 stroker, idle at 1400, turn down 3 inch exhaust. No interior at all besides seats and dash, everything fiberglass except doors. Put your had on the side of of the car and you feel the vibrations of the engine though the poly mounts. I've had this car up to 6k and 120-140mph. On start up has 80psi oil pressure. Engine has 735 miles on it. Was told if what I had was an issue that there would be a noticeable vibration unlike anything else, I have not noticed this that I recall. https://instagram.com/p/9R4l1JR0-F/ Open headers

https://instagram.com/p/627GMjR05Q/ Cold start