You lucky duck! That bike was built by Miki, and appears to be identical to the Centurion Professional (Very close copy of a Cinelli Super Corsa). Normally, there would be a digit in the serial number between the "M" and "F" for the year, but yours seems to be missing it. (I had a Centurion Pro Tour, also by Miki that was stamped with the same "missing" year digit. It's serial was "MF10125 ", putting it only 425 bikes before yours, in June of 1976. I guess they didn't catch that error for a while.) (Everything else on my Pro Tour was dated '76, making that year pretty likely.)

As for tubing, that's the decal used for Tange Champion tubing, from about 1975 to 1977. It's their top of the line, double butted Cr-Mo tubing, basically equivalent to Reynolds 531 or Columbus SL. I'm not sure if they had multiple thicknesses yet, but later they went to a number system of #1 -#5 , with #1 being the lightest, up to #5 being un-butted, straight gage tubing. The Centurion literature of the time specified Champion #1 on their Professional and Semi Pro models. I would be pretty confident assuming yours used #1 tubing as well.