VC707 SMA input voltage
Here is what I would do... and I have done this.  Provided the voltage rails of the Virtex and the raspberry PI are reasonably synchronized.

Going from RPI to V7, I would use a voltage divider, with a 1K and 800 ohm resistor in series and then hook the V7 input to the center tap of between the 1K and 800.  Tie the top of the 800 to the RPI output and the bottom of the 1000 to GND.  This will cause a 3.3V input to generate approx a 1.8V output on the midpoint.

RPI_OUT ---+
           /
           \
           /  800 Ohm
           \ 
           |
           |
           +----V7input
           |
           |
           /
           \
           /  1K Ohm
           \ 
           |
           |
           - GND


Going the other direction, as long as 1.8V output from the V7 is above the Vhigh value of the RPI, you can probably just do a direct connect.  If it is more like 2.1 Volts, the then you can use a transistor logic level shift. shifter.