Your biggest hassles will be legal ones. Find out first if (a)
the electric brakes will still satisfy the authorities, (b) if the
registration change from "Horse" to "Equipment" will present any
problems, and (c) if the insurance company will insure it after it's
rebuilt. You don't want to spend time and money building instead of
buying if the whole thing is going to be a nightmare. I sure miss the
good old days...

Dan