Watch the 440 source balancing video, then go down and see what kind of balancing machine your machine shop has. That should tell you who gets the job. On balancer and flywheels. The aftermarket ones should be neutral balanced . If they modify them for this particular engine build , every engine after that you want to use them on will have to be balanced also. Balancers and flywheels are costly enough you just don't toss them in the scrap heap.