Since the Anglo-French Concorde will stop flying commercial
missions in October, the English billionaire Richard Branson
[had] expressed interest in buying a Concorde or two from
British Airways [his business rivals].
Predictably, Branson's BA rivals refused his offer out of pure
pettiness.
That leaves Branson with only one option: To try
and purchase a couple of Soviet-era SST's. The Tu-144.
There are at least four Tu-144's in mothballs.

And I ask any aviation engineers here on Habitablezone:
Why couldn't Richard Branson hire engineers, designers
and scientists to redesign, refit and modernize those
Tu-144's?
The Tu-144's are 180 metric-tons fully-loaded.
That's a lot of alluminum, steel & titanium, etc. [1960's material technology], much of that can be replaced by honeycombed epoxy-kevlar, graphite-fiber, lithium-alluminum alloy & orientated polyethylene-fibers, allowing the fuselage and wings to be stretched to accomodate 180-200 passengers, instead of 140...and you might still come in under 180 tons.
The range of the Tu-144 is about 4,000 miles [6400km].
Predictably, there maybe ways to stretch it's range with modern
technology.

Jacob