Converting to long water pump

[PoDuck]

I've decided to convert to LWP so it is easier to mount everything I need to mount to the engine. I got the alternator and water pump new, and got a crank and water pump pulley online.

Everything seemed to be fine. The pulleys looked as though they would line up and everything would work, but when I went to secure things, the bolt holes in the water pump pulley were too narrow to fit the holes on the water pump. I understand that a water pump with 8 holes would work, but at this point, the water pump is installed, and I'm unsure about how much of a pain it would be to return it for one that would work, whether it had narrower holes or 8 holes.

Also, the crankshaft pulley has a protrusion that doesn't fit in my harmonic dampener. It looks very like it should fit, but it is just slightly larger than the hole. I'm assuming that the dampener came from the original 283, since the 72 would likely have had the LWP and I assume would fit the pulley.

Now for the questions. Why are these things not fitting? Were there harmonic balancers with different sized holes in the ends to handle the protrusion from the pulley? What makes the difference between water pumps that make them accept the narrower or wider bolt pattern on the pully?

In other words, what years/models of vehicle had each?