Just get used to thinking TLO84 for all of your summing amp needs. I assume your drawing is simplified, but the sine and cosine signals from the quadrature oscillators should go to independent summing amps. One for x and one for y. Individual gains for each quadrature oscillator are a good idea. As well a a master gain after the summing amps. An inverter on one axis of each quadrature oscillator allows you to switch polarity...
"There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso