What are your options on a 5 inch stroke. At one time Callies did not have a crank available, do they now and what are spec on this crank. If you sell the crank you have would it be worth the money in the long run going with the bigger stroke. Time and money is your decision. The old KB Company might not even be in business anymore. The New KB blocks have many changes from the old KB Blocks for the better. You might want to email or phone FHO or Barton or others that are Venders for the new KB, the owner of Marsh Performance is a member here. They all would know what your block is.