You may find a company to insure it for £80k, but being such a modified car, and high value, the premium may run in to a few thousand squids to get it covered. My BDA Elan is a very straightforward mod that only developes another 70% or so of power over the original, and Hagerty don't worry about that. A mate has a highly modified Elan with a fast road Sierra Cosworth engine squeezed in, and a lot of trick mods to the chassis, suspension, steering brakes and wheels to manage the 400 plus bhp in something that weighs 750kgs. He found one company that would take it on, at around £5000 a year for it's full value, which was around £80k also.
The only way he could get it on the road at a reasonable cost in the end was to insure it 3rd party fire and theft, and that was still a grand or so.
Strange that you can by a 1000cc bike off the shelf that does 0-60 in 2 seconds, a top speed over 200 mph, and insurance can be had for £150 fully comp!