I think this is going to look great, even without the core-accurate helmet. It's like you said, Rakshasa is about working with what you have available to you, and you certainly could have chosen a worse candidate to match with the core than a CQB bucket which imo looks right at home with the 'SPI-like' armor. Besides, in three or four years when Infinite finally has full cross-core, this won't look even the smallest bit out of place!
I'm also dropping an update though; between the files for a Commando Rifle and someone
finally coming up with the Hieu Dinh armor stls, I'm on the way to beginning my own build. Now I just really need to get my printer to work so I can at least make the weapons here at home.