Yes, a Mark IV 454 crank is "tapped" (threaded)
It also has a groove in it for a woodruff key.
I haven't done a lot of these, but this is the way that I was taught.
Install the woodruff key, and GENTLY tap it down into position using a non-marking hammer. Lube the crank snout and balancer keyway with a light film of engine oil.
Slide the balancer into position, aligning the woodruff key to the groove in the balancer. Lube the sealing surface of the harmonic balancer. (Vaseline or Lubriplate works well for that.)
Install the thick washer and use the crankshaft bolt to draw the balancer onto the crank ... BY HAND with a johnson bar, NOT with an impact. Watch carefully as the balancer begins to slide onto the crank to make sure that it's going on straight. If it isn't ... a smack with the hammer and 2x4 will likely straighten it out.
Don't be a "gorilla" ...
Never try to force it on by exerting too much force on the johnson bar ... or you risk pulling the threads off of the crank bolt. when it gets about 1/3 (?) way on, (you'll feel it) you should be able to put away the hammer and wooden block ... and just continue to draw it completelely on using the bolt.
Torque to specs when you feel that it's on all the way.