It will be about 10db less than LO drive.
Note keep all ports at 50 ohms. you can overdrive a level-7 (7dbm) DBM to as far as
13dbm no problem and that buys some headroom.
The easiest way to know is drive it with a clean sine on the audio and watch the RF
out, watch for the DSB waveform to start compressing then flat-topping. See that back up 3db.
For years, ok decades, I've used a 4 diode ring modulator with carrier balance pot.
I think its still in the handbook and has been since dirt was new.
Allison