440 Flywheel???

that is definetly a external balance balancer, see the offset weight thats in the bottom part of the balancer. its the wrong one for that crank.
the crank is forged by the looks of it. a cast crank will usually have sharp edges and thin parting lines and maybe casting flash.
i have a 318 flywheel on my 440 in my pu. as long as its 6 bolt and doesnt have big holes drilled or extra weight cast on the backside you should be ok