Yes, with a single speed instead of 7 gears in back, lots of room to change the axle.
I just meant to say that if you want all 7 ( or 7 of
gears, a large crystalyte fits fine in regular bikes. Ok, so 3000w is lame these days, but I get all I need out of 2000w or so. Running 60v, my cargo bike with an old 5304 clyte can hit 35 mph easy, and with tailwind even 40 mph, with 1800w continuous. It will climb any paved mountain road in my state, towing a trailer too. I can also dial up to 3000w, with a CA adjustment, and 72v battery.
The newer big crystalytes should be able to handle 4000w in bursts. And get you top speeds near 50 mph with 84v. Again, just get the faster wind for the most speed per volt.
In general, you can also flex out most alloy frames to 140 mm, just 2.5mm of flex per side. So cramming in a big motor might only need a minor grind to the axles to make it go. If possible, just make some bolt on torque plates that allow a wider motor, with gears, and lengthens the rear 5 or 6 inches.
If fast and cheapest is your need, then you are looking at the muxus, single speed gear, and up voltage till you are stupidly fast. grind it to 140 mm, and cram it in.