I am just coming across your post on this forum and wanted to give you the most accurate and precise information on your question. My dad has trained under the only living Master Instructor from Henry Slomanski. He is currently the Soke of Slo Ryu Karate Do, which was formed as a dedication to Henry Slomanski’s unique accomplishments, his name is John B. Burkhardt. You can read about his training on http://www.henryslomanski.net or http://www.henryslomanski.com. My dad currently holds the rank of 4th degree Shihan. We would be extremely interested in getting in touch with you further about your father’s training and his certificate. We would love nothing more than to honor your father in our lineage tree that is listed on both websites mentioned above. It would be of great interest to you and John Burkhardt to be in further contact. John Burkhardt and Mrs. Slomanski are close friends and I, along with my dad, are all part of the ventures in honoring all of Henry’s accomplishments as well as his students. Please contact me and I will put you in touch with John Burkhardt. My dad has spoken to him just prior to me writing this about your post and is very interested in being in contact. We hope to reciprocally share a lot of information. You can reach me via email @ sensei@henryslomanski.com.
We look forward to hearing from you soon! ~Daneen

Was that Wendell Reeves your dad? Let me know if it is ok to email Henry Slomanski’s wife with your email address and I will be happy to do so (not sure the email address is good but she has commented twice).
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Hope this is useful.