Take the frame and some pictures of some other TD’s with their tops up to a local Auto Top vendor. Most of them can fabricate a top.
I had a Classic Roadsters Ltd “Baron” and the top was fabricated locally out of a fabric called Stayfast, like most European drop tops use today. The guy used the old, mildewed top for a pattern.
Even if there were NOS tops for these cars, they’d be dry rotted from age anyway…they’ve been out of production so long now.
Pink MG39713.6693634259