@73TwinCamSpecial congratulations on your win, it will be an awesome car once you finalize your engine selection. I have a S4, BVTC, same color, with hardtop, and they are great, under appreciated cars.
I’ve shipped my S4 a couple of times and I always used enclosed transport each time. In the grand scheme, especially this time of year, it’s highly recommended, especially coast to coast. Each time my 7 was moved they secured straps around each tire, and tensioned as needed to prevent movement. I don’t recall them attaching anything to the chassis. Hope this helps