I grafted my UCR budwood shiranui on pretty much every combination of in-ground rootstock/interstock tree I have (lime, lemon, orange, grapefruit, mandarin, valentine pomelo, seedling pomelo, sour orange). If the budwood is healthy it doesn't seem to matter much about the rootstock, it grows vigorously and within 2 years it will be pretty large. You might want to try taking some cuttings and graft a few on any of your in-ground trees since it will grow much faster. My giant size sumo fruits seems to be on the ones that was grafted on the murcott mandarin tree. It had large fruits (shown above) every year for 3 years now, and it tastes good.