318 Poly Vibration

Meaning the metal and rubber slipping out of wack?
It doesn't appear to have slipped, and from what I know sometimes it's difficult to see.
I can certainly check again.

Isn't the poly internally balanced? But even so, a slipped balancer would be an issue I take it.

Would a 4 speed flywheel off a big block bolt to the 318 poly?
I have no desire to, but pulling the trans and using another flywheel to start it and isolate the engine seems reasonable. Must stress, not wanting to do that.