No reason to loosen the timing chain cover.
Apply a light film of never-seize to the OD of the snout and the key.
Have you given any thought to how far onto the crank snout you want to press the balancer?
This is an important initial step that will effect the final alignment of all the belts/pulleys - and it is a wicked hassle to change later on in the assembly process.
The water pump/fan clutch pulley is basically fixed (without the use of shims) and should be used as the reference point for all the other pulleys. When determining how far onto the snout the balancer should be driven, the final alignment with the water pump pulley should be the deciding factor.
It is often easiest to temporarily assemble the water pump/fan clutch pulley group and power steering pump onto the block and then use a straight edge to set the balancer depth. Another method is to actually install the common belt and set the balancer by observing the belt alignment:
