T-Mar

I agree with it being a Rekord, but not with it being a 1976. The serial number would limit it to 1974 or 1975.

As for which Rekord, I also doubt it being a 745 or 746. I have 1973 specs listing a Rekord 71 for that year. With four years between the 1973 Rekord 71 and the 1978 Rekord 745/746 models, if we assume a logical progression , it could be a Rekord 71x, a Rekord 72x or a Rekord 73x. The only thing it shouldn't be is a Rekord 74x, unless Bianchi skipped a number in the progression sequence.

The other possibility is that Bianchi did not follow a sequence at all. The Rekord 745 and 746 have models numbers with format xx.4.xx. The fact that there is a "4" in both the model names and model numbers could be coincidence or deliberate. If it's deliberate, then the OP's bicycle should be a Rekord 75x.

The bottom line is that I don't have enough objective evidence to make a statement on the model name, other than to say it is a Rekord variant. However, the serial number, in conjunction with the Campione del Mondo decal, definitely points towards a 1974 or 1975 model. The only possible way to narrow it down further would be to determine the 2nd character in the serial number.