I won't recommend trying one brand of 2-prong on a different brand FW: I have had a bad failure once with a Suntour on a Regina (maybe?) that seemed close enough...but was not.
If the outer diameter of the seat tube is Imperial (so 28.6) rather than Metric (28.0) then you have a seat tube with 1.1mm wall thickness which is rather thick stuff. Might be plain gauge tubing, not butted. If by some weird twist this is built with Metric tubing (odd for an Italian brand, but not impossible) then the tubing might be of higher grade with that 26.4 seatpost (0.8mm wall thickness).