VHF Retrofit Kit link
The kit includes the UVSJ, which selectively combines the UHF and VHF signals into one coax such that the two antennas don't interfere with each other, since they both will receive some signal they're not specifically designed to receive, which can cause problems. You may not need it, but for $16, it's kind of a no-brainer.
You don't need any additional parts with the ANT751r or the HBU11 or 22, as they're specifically designed for high-VHF (real 7-13) and UHF (real 14-51).
The ClearStream 2V would also be a good option I would think, and it includes the VHF dipole.