Balance issue… help!

[Prestidigitator]

First and most importantly your talking to a novice here.

Bought a 347 stroker motor from and unnamed big time crate motor company far, far away from where I live.

I sent them the pulleys and brackets that I had previously purchased from another manufacture.

They sent me a video with it being dynoed, with my pulleys and brackets on there and it is unmistakably my motor. In the dyno video it runs smooth as glass.

It’s a 28oz externally balanced motor.

I get the motor but unfortunately due to circumstances in my life was unable to get it installed in a timely fashion.

By the time I get the motor in and running more then a year has passed by and the warranty is now expired.

The motor fires up and sounds great, one problem though it has a pretty bad vibration.

So once I get the mufflers on it and start driving it I can’t seem to figure out this bad vibration.

I take it to a few guys I know and they all come to the same conclusion that it’s a balance issue.

Right now it is at a shop of a fairly supposed well respected motor guy.

He tells me it’s the balancer in the pictures and video and that the flex plate is indeed a 28oz.

Yet, the motor still runs rough.

He tells me there is about 6-9 different combinations he is going to try to get the motor to balance without taking the transmission apart and taking off the flex plate (as I understand it).

Does any of this sound copasetic to you?

Is this how you would go about it?

Any help would be greatly appreciated and the more input would be helpful.

Thanks so very much.