While it's not the greatest image when enlarged, the photo shows that the medial side of the right rear dropout has the raised circular boss that was added for mounting the Portacatena chain device (see pic). Given that Portacatena was introduced for the 1978 model year, the frame should be no older than this. The other end of the time frame is a bit harder to peg down, as builders often had excess stock of dropouts lying around after the product was discontinued.

Given the additional picture showing the bottom bracket shell treatment, I have no reason to believe this is not a legitimate Tommasini.

The lack of embossing, particularly on the fork crown, suggests that this could be a tretubi version of the Racing model. I'm not aware of Tommasini having produced any frames below this level (i.e. Aelle or Zeta) but it would be interesting to know the seat post diameter and whether the bottom inside of the fork's steerer tube has the five helical ridges indicative of a Columbus steerer. This would aid in determining the frame's tubing configuration, given that there was some variation in the Racing models.