IIRC, BG used to make a drop-in replacement for the Carvers in their RD series, but since the company was sold they seem to have stopped selling the RD's to the public.
If you're considering vintage speakers, I'd recommend that you go with a brand for which there's good support. Magenpan still supports their old models and you can rebuild them yourself with a kit or send them to the factory. And there are people that rebuild Quads. Not sure what the story is with the LFT-VI, but of course the company is still in business. Acoustats are pretty much indestructible and Apogees can be repaired with parts from Graz in Australia, but it will cost you an arm and a leg, making it a less economical option.
If you're considering vintage speakers, I'd recommend that you go with a brand for which there's good support. Magenpan still supports their old models and you can rebuild them yourself with a kit or send them to the factory. And there are people that rebuild Quads. Not sure what the story is with the LFT-VI, but of course the company is still in business. Acoustats are pretty much indestructible and Apogees can be repaired with parts from Graz in Australia, but it will cost you an arm and a leg, making it a less economical option.