4G15 sohc cranks different? urgent help needed!

Okay so I bought a nice clean 03 ce mirage. engine had a knock, pulled motor out and stripped her down, 2 spun bearings, got a new set of bearings, then 2 rods and a crank second hand. crank was out of a 98 mirage. so apparently there are differences in the crank, my balancer bolt and timing gear are too big for the new crankshaft. so my question is what are the differences between the two and what is needed if i was to keep this crank? if i just went to the wreckers and grabbed a balancer, bolt and lower timing gear? any other bits that need to be addressed? or am i better off pulling it out and sourcing the right one?
Pretty urgent matter as this will be my new daily due to the trusty magna being too thirsty!!