I'm currently restoring a single cylinder B model Harley side valve generator model, I have a 1926 frame with a 1929 motor 29B1946 and its coming along ok. I have another bottom end with the engine number A2995 and I was of the understanding that the A model was the overhead valve model ? is this correct the casings are similar but a small difference on the left hand side . Any information would be greatly appreciated.