I have seen and heard of people building the hull of the smaller model, slicing it into sections and then using them as templates to scale up and create frames to the scale required. Yes you lose the kit hull, but this should be cheaper than ordering from abroad.
I appreciate what people have said about scale creep due to enlarging an innacurate model, but as the percentage of innacuracy will be the same, it would not look out of place. 2% on a 1:300th scale model will still be 2% on a 1:96th scale model. The innacuracy will not increase disprportionally. Obviously if it is more like 5-10% then that is unacceptable and I would not reccomend it, but the thickness of the planks or a little difference would not look out of place. By all means choose what you want to build, but do not worry about a little innacuracy if it does not stink Malcolm.
Also, unless we all start walking around with tape measures and books of stats, we will not notice any difference