“I'm thinking of moving it to the void just rear of the rear torsion tube, near the transmission. It would save me a bunch of oil line. Thoughts?”
Having a shorter hose run is always good, but I am not a fan of putting an oil cooler in the void between the firewall and the rear of the back seat - the air flow turbulence just ain’t sufficient to make it efficient.
Instead, mount a fan assisted oil cooler in the driver’s side rear wheel well. Close to the engine and gets plenty of cooling airflow.