Engine shakes BADLY!!
Yea, I was thinking a step or two warmer on plugs.
Just to go one step out of the norm, since your mounts are good and not solid/metal, did you have the K frame out during the engine work? Could there be something loose or even a header or exhaust banging on something causing the shake/vibration feeling?
I'll step out and see how things progress. If I have any other thoughts, i'll chime in. Good luck, sounds like you have really good potential with the combo you put together. :thumleft: