I do wonder, when 350bhp.is hot hatch territory today if some cars are a case of 'dont meet your heroes'.
I understand a massive chunk of value is tied up in nostalgia and image but I do wonder if it would be 'worth it'. I struggle with quite a lot of classic car pricing today. When a Ford Sierra (and not even the really quick ones) will set you back more than an Aston, I feel like I've missed something somewhere. 
I think what made the LC special is, even today, it's not short on power, and there were no real compromises, its a big, comfy semi-exec saloon. You can hold a conversation in one at 140 (so I've heard, obviously) easier than many cars doing 40 without having to raise you voice. And its 35 years old. Thats how ahead of it's time it was.
At the time, the Granada was a crock with that old 2.8, though shortly followed by the better 2.9, Rover was doing the 800 Vitesse, and that was about it for European big execs.
Obviously, from a technology and gadget perspective, if thats your thing, its badly dated - mobile phones weren't really a thing for most people, let alone smartphone control of the car. Looks wise from the exterior it looks like, well, a 1990s Vauxhall.
I wouldn't own one now, because I would not be able to keep it in the condition it needs to be kept in, and few remaining need to be kept tip top for the future.
A true icon.