Many attempts have been made to make a working patch, but none of the files currently uploaded to the Nexus is up to the task. It took all day, but I figured how to make things right, learning from others' mistakes. Now the mods both work as intended, with a visor, viewing modes (Heat, Nightvision, EM), AR Scan and damage visuals. The Visor used is the one used by the Vault-Tec Power Armor Helmet, as it shares the same structure of the one introduced by The Legacy of X13. The colour of the visor is black since you can see from the screenshots the lens are dark, no matter the type of armour textures you choose. 
Lastly, there is quite the variety of armours you can craft in the original mod depending on which upgrades you install first: some of them activate a stealth field when you crouch. Fear not, they are fully compatible with Project Nevada: by simply replacing the script with a similar one without the stealth field, all I had to do was adding the cloak mode featured in PN, so you can turn it on and off at will. This way everything works as both mods intended, and everyone is happy.

REQUIREMENTS:

Old World Blues (obviously)

The Legacy of X13 - An Armor Overhaul (http://www.nexusmods.com/newvegas/mods/42911/?tab=1&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fnewvegas%2Fajax%2Fmoddescription%2F%3Fid%3D42911%26preview%3D&pUp=1)

Project Nevada (http://www.nexusmods.com/newvegas/mods/40040/?)

Have fun!