I found some websites and pictures that you could find interesting; the soldiers that are pictured are not specifically Romans most of the time, but I guess their equipment was not very different from that of other Italians. I have not found XIIIth century italian soldiers depictions yet and only a handful of XIVth century ones, I rather found XVth century representations.
Frescoes and tapestries seem to be underestimated sources of informations.
Of course the artistic representations should be manipulated with caution, it is a commonplace that illuminators and painters from the Middle Ages didn't have the preoccupation of representing accurate or realistic scenes, but I guess I do not teach you anything.
This website covers XIVth to XVth centuries with some paintings amongst the most well-known :
http://www.warfare2.netai.net/14/Ita...4thCentury.htm
Scenes from the Massacre of the Innocents fresco in the Sant'Abbondio basilica, Côme (1315-1324) :
Knight of Pratro, XIVth century, Tuscany, probably painted by Pacino di Buonaguida :
https://www.bl.uk/catalogues/illumin...id&IllID=42522
Codex Capodilista, equestrian armorial intended for Transelgardi, Forzate and Capodilista families, around 1435; some of the coats of arms are fictional (sorry but I only found a french page mentioning it, many of its illuminations are hosted on gettyimages) :
http://behydezell.com/article/creati...ex-capodilista
Paintings from the church of St Stephan in Obermontani, Morter, Italy, 1400-1410, obviously very close to german-speaking countries :
http://armourinart.com/119/165/
Saint Georges by Andrea Mantegna, around 1460 :
Finally, and even if many of them are already depicted in the mod with few variants, some XVth century italian helmets :
Barbute from the Chalcis venetian garrison, 1350-1420 (they don't say anything about the coat of mail's origin) :
http://www.clevelandart.org/art/1923.1065?f[0]=object_location:Gallery%20210
Sallet from the venetian garrison of Chalcis, mid-XVth century :
Italian sallet, around 1450-1470 :
Italian great bassinet, XVth century (sorry but I did not found a smallest image) :
Italian great bassinet, early XVth century :
Milanese "armet à rondelle", XVth century :
http://www.clevelandart.org/art/1916...m=All&page=1&f[0]=object_location:Gallery%20210