Wow, thanks for all the replies, sounds like it won't be too difficult to get an extra 50bhp then and shouldn't add too much stress on the engine.
I spent in the region of £5k on my supra in mods and had an easy 420+bhp but I don't want do do this again, getting older and wiser!! Just a few light mods like exhaust, cats, maybe chip will be sufficient.
I'll keep an eye out for a car now, not looking to buy till after summer really. I've been quoted £440 insurance on a UK spec car which was a pleasant surprise, I guess it'll be a little higher on a JDM car.
Thanks again everyone.