65 D100 /6. swapping in a BB. Have the correct BB (early 60's I am assuming) hyd bell/wheel/ NP 435 granny 4 speed etc. I am assuming this 'wheel is internally balanced. I have a 400 & a 440 & the torque converters on both of em have the extra weights denoteing externally balanced (I am assuming). Is there any way I can get one of these engines to drop in as is or do I need to find an earlier internally balanced 440? Thank you for your time.