I don't see anything out-of-sync. Hi-tensile tubes cover quite a range of wall thickness. Some of the high carbon versions did use 26.0mm posts. The next model up, the 850, used a tubeset that required a 26.6mm post. The italic font on the down tube is correct, and was used in conjunction with the standard logo on the seat tube, though as stated previously, they appear to have been trimmed. Other Benotto models from this period used Ambrosio and Nisi rims, so they're probably one or the other.