You can run unleaded, toyotas have had hardened vavle seats long before 1986.
choose your own adventure
1. PULP 95 octane, no adjustments. EDIT Standard timing 5° at 900 rpm
2. ULP 92 octane, need to retard timing, i can't remember correctly, but it may be 5 degrees. EDIT Modified timing 0° at 900 rpm
1. You drive off happy into the sunset with full power.
2. You lose all of diddly squat and are still happy because it's a LASRE 4A!!!