The first principal of “matching” two cameras is to set them at the same frame rate and scanning standard. This presumes you want them to look alike, not different, so if Varicam is shooting 30p, then set the HVX to do the same.
Next would be to try and match the gamma curves, so that if the Varicam is in Film Rec 200% Dynamic Range, the most likely match would be one of the Film Look settings on the HVX. This is a guess, the only way to determnine would be to look at a chip chart with both cameras and adjust the various gamma tables while observing on a waveform. This will optimize the luminance match (shades of gray).
Then as for color, using a Chroma du Monde or similar color chart and the vectorscope, you’d want to adjust the matrixs to match.
Short of these efforts, set the cameras at same frame rate, white balance, black balance and shoot.
Good luck,
JS