The Scanyacht 290 was a version of the LM27 produced by Scanyachts in England after LM stopped building them. Scanyachts was the agent/importer for LM in the UK.
The Scanyacht document below has various drawings and info about the Scanyacht 290, including a comparison of dimensions between the Scanyacht shallow and deep draft versions, and also the original LM27.
The most obvious (to me) differences from the LM27 are:
More ballast (by using lead, rather than steel/iron for ballast)
Availability of a deeper keel version
Lighter overall weight (as the ballast had gone up, presumably the hull was built lighter)
Availability of a two seat wheelhouse option, with the galley replacing the port hand bench/berth in the saloon.