416" harmonic balancer needed

I can't get a true measurement because the radiator interferes with the opposite end of the dial caliper. But the damper/balancer ring is less than .840" thick. Pioneer part # is 872037 (neutral balance). The catalog I have lists the thickness as 1.20", but that is obviously a misprint. It probably applies to their SFI 360 external balaced version. Just to confirm the measurement, you can ask whoever you buy one from to take an actual measurement right out of the box before buying it. Mine has almost 3/8" clearance between the ring and the timing marks on the cover.

An OEM 360 balancer/damper is around 1 1/8" thick and I never had an issue on any engine. It is very possible that the one you have is machined incorrectly, possibly using incorrect measurements/specs.