If the car is standard then try the insurance supermarket for quotes and a local broker. If the car is modified (I think adding a skyline engine counts as a slight modification then Adrian Flux, Norwich Union etc...)
See our insurance article here for a guide on how to get cover for modified cars.
i sold the peugeot with the skyline engine, turns out a small problem is very difficult to repair, plus its in the back, so i sold the engine seperate put the standard one back in, i got another peugeot 206 gti