Pulley Alignment

My 69 340 has a 6 7/8 water pump pulley and a 6 1/2 crank pulley, currently. The car isn't running yet, but I am in the process of adding classic auto air and would rather figure the correct pulleys, for the best cooling, now than later.

I have a 5 3/4 water pump pulley in my stash, however it is shorter than my current one, so it doesn't line up perfectly with the crank pulley, it is close though.

What is the best way to shim the crank pulley forward, Can I put some washer behind it and use a little longer bolt?

Thanks in advance.