The "F" indicates that it is a 1970 motor, and other than having a slightly milder cam than the "Magnum" grind of the HP motors, I would assume that all the other internals are the same. The heads are probably 904's if original, or maybe 452 replacements for the hardened seats. A slightly hotter cam and your converter upgrade should do that motor wonders. Unless it needs a rebuild because of high mileage, or it's tired, I would add some aftermarket upgrades such as your plan and hot dog it until something happens to it, then tear it down and upgrade the internals a bit!! JMO, Geof
By the way, why do you think it's externally balanced?? Does it have a large, somewhat tapered front balancer on it?? Could you show a pic of that?? If so, it could have a later cast crank in it, which would still be good for 600hp, and then you would need the B&M flexplate to use a zero balanced converter!! Geof
