IMHO, you wont be satisfied with that cheap, sloppy Italian tang sight. It will be OK for a little while, at best, then you, like most who buy them, will get something better (unless you really arent serious about this). Then what do you do with it? A 'schuetzen' staff height will get you out around 300yd, a short staff even farther. Unless you entertain 1000yds. you wont need a long staff. BTW, if you buy a tang sight with a more common and desirable between the hole mount, like for a Win. 1885 (high or low wall) it will be a lot easier to sell if/when you want to upgrade. The staff angle will be right when flipped up, too.
Regarding mounting. You do not need a metal tang to mount the sight base on. A lot of old original rifles, without 'tangs' had one mounted right on the wood. You can too. You always sight in on a new shootin' day anyway, right? Ignore the warnings about the sight shifting due to humidity, etc. No matter which way you go on this, remember the stock bolt hole is not that far below the surface.