440 duster. Need engine build advice

1st thing I would do is a little research on what you have,does the balancer that was with it as well as the flexplate/convertor have weights or other,may have already been balanced if weighted items are neutral...cast cranks are good upwards of 600hp,and if its already been balanced it will appear to be a forged crank with neutal balance,pull pan and chk numbers on crank then you will know,or visit with the fella you got it from and find out whats what if thats possible,if still in doubt then load it all up and have it chkd out or put a forged unit in,even then I would have it balanced,for me a balanced engine is a happy engine and you will get more out of it and less probs....If its a 69 440 it will be a forged crank...