My word, does that take me back! I had a '59 Minx saloon, which had some of the same mods.
The cylinder head has been replaced by the Sunbeam Rapier head - could be Alpine, too. Notice the unusual port arrangement EIEIIEIE vs the much more usual EIIEEIIE (or with siamezing). That means the camshaft's been replaced, too.
I did that to my Minx, but with the Rapier O/D gearbox and propshaft too.
It's also got a Sunbeam fascia, or partly so. Minxes didn't have rev-counters - there was a combination gauge (fuel, oil, water) but I see it has auxiliary gauges ahead of the steering wheel.
Pity it's an automatic! Still, it should command plenty of interest.
I wonder if the brakes and suspension have had due attention paid? I'd guess so, because the brake servo is non-standard, too.