Danjo
Master Black Belt
I think that you should go to an instructor and talk with him/her. Tell him of your prior experience. Be ready to demonstrate your techniques and kata, and accept the instructor's judgement as to where you should start. I have a 3rd kyu in Shotokan from many years ago. I still practice my kata at least three times per week (1-5 Heian and Tekki Shodan). I never want to lose what I learned. I also have a 3rd "degree" (3rd kyu) in Shaolin Kempo Karate,and I keep up practice in that too. The kicks, blocks, punches and stances are very close to each other. If an instructor looks at your skills and says, "You're a white belt", then there may be a problem. (either with the instructor, or your previous training). If you look around at the other white belts and you are clearly more skilled than they are, perhaps you should look elsewhere for an instructor that can more fairly assess your ability.