Well, after doing a bit more digging on this site, I've found a fair amount of people saying that leafbike is pretty decent hardware, so I ordered the kit and battery posted above.
I had them use a rim for a 20x2.1 tire so I could get a little more tread patch than the 1.75 tire that the shuffle comes stock with. Even with the shipping I'm still only into the motor for just under 500 to my door. Now the deconstruction/ reconstruction begins!
I'm going to order this rack for the controller and battery pack to mount on:
https://www.amazon.com/M-Wave-Alloy-One-4-All-Bicycle-Carrier/dp/B007Y5EP7S/ref=mp_s_a_1_6?dchild=1&keywords=20+inch+bike+rack&qid=1576544097&sprefix=20+inch+bike+ra&sr=8-6
I'm also going to go pick up a bunch of aluminum diamond plate from the orange big box hardware store to make a box for the battery, as well as a skid plate along the bottom of the sled. Just to help with frame stiffness and also to, you know, be a skid plate. I know nothing of welding, so I see a lot of screw clamps and jb weld in my future, lol.
I really like the handlebars with the basket that was earlier in the post too, lol.
I'm definitely going to make a new deck for it. The deck that comes stock is just... well... cute? Seeing as how I'm not really going to be kicking the kick scooter a whole lot anymore, I can afford a few more inches of width out of some gorgeous hardwood. I'm thinking mahogany? Ipe? Zebrawood? I'll have to go to the lumberyard and see what speaks to me, lol.
Once I have all my parts on hand, I'll start taking pictures.