This is the Leo Type IV (or Grief/Gryph) as depicted in the ongoing Gundam Wing novel Frozen Teardrop and the comic book reboot Glory of Losers. According to the pic, it features rear thrusters and a shoulder cannon from 2 other mobile suits in Wing. Both have their own model kits but apart from being extremely rare, they're resin kits costing a lot of money. Since I'm not made of either, I'll combine 2 kits that resemble Type IV the most.
Luckily I still have an extra 1/144 Leo I've bought a few months back, along with a 1/144 NG Tallgeese II, which has most of the parts that I need. Since both kits have a similar construction and use the same polycaps, it reinforces the idea that you can mix and match kits from the same line of Gunpla.
Parts and accessories for the Leo
Parts and accessories for the Tallgeese II
All that's left now is to gather the necessary tools for the modifications I have in mind. I figured I'd look around in my city's Chinatown, which has several anime and hobby shops. But all I got was steamed pork dumplings and orange gummy hearts (both of which were pretty good). So now I'm ordering everything online and I estimate it'll be at least a few weeks before I can actually start this project. Until then, I might go back to Chinatown for some beef or chicken dumplings.