I agree, even though you're going to restrict the bike its not going to restrict the bike or change the risk analysis the insurance companies use, so you're going to pay through the nose for the insurance.
as for restricting the bike, with you're budget you're looking at something like an '03 model; restricting it to 33 bhp is going to knock of the power to weight ratio. I ride around london in a fairly large group and theres a restricted r6 and kwak 636 amongst us which always get left behind the kwak 250 and the derestricted rs 125.