Scarlatti does not need a big French double but rather a big Italian double.
There were some. Wm Dowd went on a tour of South America looking for Italian &
Spanish instruments years ago and turned up large Spanish doubles, false
inner-outer, which would have suited Scarlatti compass-wise. I built a false
inner-outer dble 63 note for myself and my husband - we both like to play
Scarlatti. Strung in brass; sounds great. An excuse to do a fancy decorated
case & turned legs, nice after a diet of veneering and Biedermeyer case styles.