Is my balancer seated?

[Longhorn321]

OK experts....How do you know if your harmonic balancer on your 350 is fully seated? I used the center bolt and a washer to pull it on and it went most of the way but I think it may need to go a little further. The bolt started getting harder to turn and I started getting concerned about breaking the bolt so I stopped. The crankshaft also started turning which leads me to another question...What's a good way to hold the crank so you can torque the bolt properly? Any tips would be greatly appreciated.