99.9% of S1s will require a frame change. The frame is fully enclosed and water and crap splashed up by the rear wheels makes its way under the frame and just sits there. Unlike in the later models, the frame is sandwiched between two bonded body sections. The frames are also not available. You have to modify an early S2 frame to suit. It's a big job. Just doing all the glassing after changing the frame took weeks.
All that to say that it is easy to understand why someone's heart may have gone feint and they decided to move the project along.
I have an S1. I changed the frame. I love it. It was a LOT of work.