The 92 Victa alloy base might be dual drilled.
Power torque motor is the same pattern as a briggs that is mounted sideways. Ive a few here with 5hp quantums sideways mounted but i think they are a bit newer.
Most of the bases (from the mid-late 80s on) were dual drilled as they turned the Tecumseh motors around so they faced forwards. And then later the briggs sprints etc with the spacer rings.
Probably best if you start your own thread in the Victa frames section and put some pics up of the mower.
