I don't think I've seen many G40s hang about this long bar the dreamers wanting £5k+.
You're right when you say the reason you haven't got much interest is because it is LHD. A RHD G40 in the same condition would have easily sold by now I'd say.
If you do break it you'll make at least two thirds of the asking price by selling the engine conversion, interior, brakes, wheels and TCAs etc. But the rest may take time to sell.
If you do break I might be interested in some bits, but it would be a shame to break such a clean looking original G40.