It's easier to install the timing gear on the crank AFTER it's in the block. The timing plate gets installed after the crank is in, then the gear is pushed into place. It's steel, so you can get it hot enough that it almost slides all the way onto the crank with a gentle push (wear a welding glove- - - -it's much less painful that way!). Wedge the crank forward with something to keep the load off the thrust bearing flanges as you tap the gear home. I use a large-diameter deep socket as a driver, and moderately firm taps with a BFH.
Jerry
