Transmission Swap?

Hello fellow Forte enthusiasts,

I have a 2017 Forte5 SX (1.6T, 6M) with about 85k miles, and I've owned it for a little over a year and about 20k miles. For the most part, it's a fine little car, especially for what I paid (Thanks previous owner for taking the depreciation 😉). One of my main complaints about it, though, is how short the gearing is, especially in 6th. I do a lot of highway driving, and 3k rpm at 70mph gets old pretty quick. Thankfully the stock exhaust and interior do a pretty good job of masking the noise, but I only average about 32mpg, which for a little car with a little engine, especially with it being only 4 years old, is not grand. I'm also not thrilled about driving for hours on end at an RPM I rarely see on the street (yes, I granny shift the heck out of it).
So naturally, when I found out that it's Hyundai sedan contemporary, the Elantra Sport, has longer gears from 3rd-6th, it piqued my interest. And when I saw that I can purchase one of many used transmissions on eBay for $400-500, that comes with a (short, but free) warranty and return period, and that came out of wrecked cars with half or less-than-half the mileage on my car, I became very, very intrigued as to whether or not I could swap my transmission for one from an Elantra Sport for some better mpgs, less highway NVH, and less engine wear.
I'm wondering if anyone here has any information at all about anything that might keep me from being able to do this, i.e. if the mounts are too different to work, different electronics, different axles, etc. If not, I might find myself with an extra transmission once I notice my clutch beginning to give way, and test fit the Hyundai trans in my Forte while it's trans is out to see if it's potentially possible.

P.S. This is my first time ever posting in a forum, so if there's something I did wrong or can improve upon, feel free to leave constructive criticism in the comments. Thanks!