If it looks like a 172, you may well get stung with your insurance.
Mate of mine had a 1.2 Corsa, made it look like a GSi, I mean went the whole hog so you couldn't tell it apart. The insurance he paid was not far off that for an actual GSi, so he would have been better just to get one and done with it!!
Its your money and your call at the end of the day!