Well people do not always agree but the A was designed to run 55 MPH so one should ask what Ford did?
You will find the engine was built to a high level of precision. No just slapped together as many will tell you.
So you need to take some time to understand how Ford actually built the engine and learn from that.
The crank as well as all the moving parts were held to some very high standards. If you handed the prints and the parts to a rebuilder and asked them to make it like new they would tell you that you wanted something built to racing precision.
To your question what do you need to know about cranks?
See the link for some thoughts.
Some Crank Notes
You can spend a lot of money building a perfect engine. New head, new crank, insert rods, cut down flywheel and the list goes on and on and on.
You can also go a la cart and pick the important things as your budget allows. The minimum is getting the engine back close to Ford specs and very well balanced with all the parts.
Keep in mind you can spend a lot of money on various parts and just neglect one small detail like the correct valve clearances for the type of metal in the valves and it will not run right.