The timing marks change, correct.
I once saw a small block, cast crank, break in two directly behind the factory stock balancer.
When the engine was rebuilt the foul put the stock balancer back on, but couldn't get the engine to run because the timing makes were incorrect.
Would not have believed it if I had not seen it with my own eyes.
Let the OP ship you the balancer and you can test it for us on one of your engines. LOL