I did something like this in HS. We would pull them out of the garbage in the projects (project people in Malden always seemed to have plenty of money, henceforth kids in the projects always had the best toys, and being spoiled, of course they destroyed them in a matter of weeks to the point of Power Wheels being used as a fulcrum for a bike jump, etc.) and stockpile them at the auto shop at school. Mostly the blue Bigfoot ones.
On one I added flashing lights to the front and rear using a flasher from a car, a deadman switch on the steering wheel since you'd need to be 2 feet tall to access the original foot pedals, the seat was moved back over the bed, and the stock battery was replaced with a deep cycle RV/Marine one. LOL
It went noticeably faster, and I custom painted it. We had another with tandem RV batts and I forget what else. We'd drag race them across the parking lot and also through the halls of the school down near the shops. One caught on fire and everything kind of fizzled out after that...haha
Supposedly the body of the one I made was saved at the school because of the paint job