check to make sure the dist gear doesn't have any sign's of wear on it,mine did that put a new gear and rotor on it,rock solid steady.

Some timing bounce is normal in an engine that the pick up module is with in the distributor.

It is due to the gear lash on the cam gear and distributor gear. Also, the cam end play will play a major part in timing bounce. As the cam walks back and forth in the block, it will cause it to bounce. Not as evident in flat tappet engines because the the lifters tend to keep walk minimal, but rollers you'll see a little more.

With that said, you can get bounce to a minimum by the use of cam button.and new ditributor gear.

If that doesn't make it acceptable, then theres always a crank trigger, after all, that why they were invented.

It's a TB 4 for sure. I am running a roller and do have some gear wear on the Dist. I loc-tite'd one of my rotors to see the diff,,haven't tried the light yet but it did have a lot of play in the rotor, I'm thinking that was it. Thanks