I love Mother 3 OST and it's one of the OSTs that influenced me years ago when I first started out (particularly in bassline writing), so its not a reach! And yeah if I had more time I probably would developed and reused the 7/4 section more. Crunch hit me hard on that track haha.
Trust me, I also have trouble finding brass sounds I like lol. It's a patch from the Roland Edirol SD-90 synthesizer called "Romantic Trumpet"! It's also known as the "Touhou Trumpet" and you should be able to find a free soundfont version in Touhou and Undertale soundfonts. You can also find a paid VST version in Roland ZENOLOGY and I believe Roland SRX World. I layered it with the guitar to make it sound fuller.
The guitar was done using Ample Guitar SC.
Thank you so much for the detailed feedback!