The elements would need to be shorter to be resonant at a higher frequency. You might be able to make it work with just the gamma but that doesn't fix your problem, it would just make the swr tolerable for the radio. But there is more to it than just swr when it comes to changing bands. We can probably help you with the calculation, but we will need to know what frequency you want to tune to exactly. This will set the middle of your range so you will be good above and below this point for a certain amount. Maybe someone more knowledgeable can elaborate.
Chris