What year Escort is it mate? If you got a 1.3 CVH in there your best and easiest upgrade would be to drop a 1.6 CVH in its place, keep it on carbs if its on carbs already
Forget the insurance companies mate, unless your dropping a cossie lump in there, they dont really need to know! Makes me laugh when people worry about telling the insurance companies about swapping parts on their cars- people come over all honest and tell them every nut and bolt that might possibly be non standard like the insurance companies are the goddam police or somethin... i say f**k em! theyre just an insurance company! people scam phone insurance companies to get a new model mobile without theyre concience coming into play, why is it different with car insurance companies?!?
Its highly unlikely they will send anyone out to look at your car if you do crash and claim, and even if they do, theyre mechanical expertise only goes as far as knowing how to operate the button on the top of their biro's, so they wouldnt know a zetec from a CVH anyway!
rant over!!!
Got any pics of your project mate?

street