Moved my 1990 GT-R to Shannons this month.
Spent about 30 mins on the phone with underwriter. Started at 21k. Went to 25k once he started looking at comparable cars on Carsales. He upped it to 30k when I explained the engine had been rebuilt etc. It seemed like a reasonable way to work through it.
Based on this, I will do some research leading up to renewal next year to see where prices are at.
30k would not come close to covering what I have spent buying and having built - that is a different story - but it is a lot closer to buying something comparable than I would have been previously.