[NOT A TA]

The first step is to drill out the new body mount holes with a 1 1/2" hole saw and then open them up a bit more to 1 5/8" with a carbide bit on a die grinder.



You can see in the pic below that a solid body mount won't sit flat inside the frame because of the sheet metal overlap where the frame is welded together. To fix that problem and strengthen the frame I modified some big washers to be welded in later. a small part of the frame end on one side also had to be trimmed out to allow the subframe connector to slide in later.