Ramp employee reported a dangerous situation when a 777 started engines for taxi while a 737 tow crew was nearby. The reporter stated there needs to be a change in policy to improve safety.

Narrative

I observed Aircraft X (777-200 operating as Aircraft X to ZZZZ) begins pushing back from the gate going to a drop spot. At the same time Aircraft Y (737-700 operating as Aircraft Y to ZZZ1) begins pushing back from another gate to another drop spot. I was on a tug vehicle talking with Ramp Assistant Manager behind the aircraft at a gate [near the 777] as these pushes began. I told the manager I was going to drive along the wing walker on the aircraft's right to get a sense of the jet blast potential when the 777 started up the engines. I observed on the aircraft's right the tug vehicle with the wing walker. The force of the jet blast was substantial and made the tow bar disconnect and the final marshalling - aircraft dispatch difficult for the two agents. I returned to the manager to discuss what I experienced and what he had witnessed and we were in agreement that a safety report needed to be filed for the jet blast exhaust hazard created by the spacing between the two aircraft and ramp crew when the 777 started engines and began the taxi out process.