416" harmonic balancer needed

Are you sure they didn't ship you a big block damper/balancer? They have a shorter snout, which sucks it into the timing cover. But it will fit on the crank!

I've been using Pioneer SFI neutral race balancers on my internally balanced 360 for years. Summit carries them and I believe Jeg's sells them under their label.

Summit: http://www.summitracing.com/parts/PIO-872037/