Engine Vibration in Reman Sparton Engine
Keith sent this inf - wanted to share it

Keith
I would check the balance shaft timing. If the balance shaft timing is off, that would be the fault of the reman company, not the mechanic who did the install.

The other thing I would check is to see if the rocker arms were properly torqued if these are individual rockers. If it is a rocker arm assembly with the rockers on shafts, then that would not be the issue.

If this has solid lifters (solid cam followers), then a check of the valve lash would be in order. That should be done soon because if the valve lash is zero, the valves will burn up in short order.