Ehh...yes and no.
Yes, the VHF RF board will physically plug-n-play with the UHF decoder board, and will probably work just fine...BUT...
No, it won't be an optimal setup, and you might notice decreased performance, especially in areas where the RF signal is not very strong.
The reason being, there are two key differences between the VHF and UHF models.
The first, and most obvious to the naked eye, is the antenna. The VHF models (both low and high band) use a much larger bottom loop antenna on the decoder board, it covers just about the entire back of the board. Contrast that with the UHF model, uses only a thin piece of metal for the bottom loop, similar to the top loop antenna on the front of the unit.
The second difference is that the UHF model uses a capacitor between the bottom and top loop antennas, whereas the VHF model has no capacitor, the connection is made via a jumper.
Give it a shot and see how it works.