From what I've seen it'd be about the same degree of work as converting CT to HG. There are differences, small but significant enough to require reworking, from even the little I've gleaned of the design system.
That's always been an issue though, for every new design system in Traveller. Annoying in a way, especially when each system then gets used to spit out the classics with no thought to the differences. The oldest canon example probably being the X-Boat. Designed with 1st Ed LBB2 rules it made no sense in 2nd Ed LBB2 rules and should have been re-imagined. Even more so when HG really made the original design archaic.
I'm sure you can re-imagine any classic design with the new rules. How easy that is will depend on what your goal is in reworking them.
Or you could just use them as is, treating them as archaic low tech examples.