Harmonic Balancers

I installed an ATI on the 340 in my Dart Sport project. Engine is zero deck with JE flat top pistons, Comp Cams solid flat tappet cam, Eagle forged crank and H-beam rods, Edelbrock heads, 780 Holley, and RPM air gap. Engine is broken in but not driven, project build still in progress. I went with ATI because of my success using one in the mini-stock Ford I raced for many years. Before switching to ATI, an engine rebuild was required after each season, 15 races. Once I switched, we could open up the engine at season's end and there was next to no wear on the bearings, both rods and mains. Clearances were still tight. Engine was noticeably smoother throughout the RPM range, in race trim 5500 - 8000 RPMs. With all the inherent harmonics in those 4 cylinders, I was convinced.
One note - on the 340, I had to grind away part of the cast-in timing marks to get the balancer seated as far back as it needed to be. I ended up grinding off about half of the markings and welding the opening shut from inside the timing cover.