So why not just hold off with doing it down the track? Whats the point of high mounting it now, spending a few hundred dollars trying to get it mounted (cooler piping, dump pipe, lines, gaskets, labour) losing performance, having it looking stupid and then spending more money down the track on the way you originally wanted?
But to answer your original question of course you don't need a "taller" bonnet, only time you would have an issue is with a massive truck turbo, a poorly designed custom manifold or a twin cam RB30.