Thanks for the tips. The instructions that come with the Moss kit talk about square washers being used where connecting to the trailing arm at springs, but did not include "square" washers but two large heavy round ones. I was concerned they would shift. Think I will find or create alternates, so they stay in a fixed position. Also the directions do not talk about a backing plate where you tie into the frame, but does include backing plates. Would have to assume more than one person had a similar problem. Would be nice to back it from inside, but do not want to make an unnecessary frame patch.
Side note, Liked the “toys” on Adrio’s site. Ran across a ’06 limited edition Miata this weekend with 8000 miles. Drove it a couple of days trying to find a good excuse to add it as a “toy”. Just to keep the wind in my hair until the 6 is ready to roll. Afraid I might get use to smooth reliable comfort going with the wind blown look.