Slant 6 to 340 Engine Swap in 69' Dart

sorry, I am old school, and go original only. When I put mine together I use only original equipment. So my advice goes that way, I'm not saying the other way is wrong, just not original. I bought some aftermarket mounts once to Install a crate 426 Hemi in a 67 440 GTX. what a joke, the engine shook the car all the time, and the mounts did not align up properly,,,and The mounts were too rigid, etc etc etc
Just my experience, maybe others had good luck with it.