Highslots - 800mm autocannon IIs with Barage ammo for ranged and Republic Fleet EMP for close range brawling.
Mid Slots - Xlarge Shield Booster II, 2x Shield Boost Amp II, 3x Invuln Field II
Low Slots - Damage Control II, PDS II, 3x Gyrostab IIs
Rigs - 3 x Large Projectile Ambit Extension (the falloff increasing ones)
You'll need a cpu amount implant, but you can get a over 800 dps with the EMP out to 25km or so accurately, or switch to the barrage and drop to 650dps out to 50km. The oversized shield boosting really pays off at high levels of minmatar battleship, as i can get a tank of 1100 or so, though only sustainable for just under 3 minutes. That said, if you can't kill something in 3 minutes, you'll likely die yourself.
Round it out with some drones of your choice (likely warriors or hobgoblins to help with frigates) and you have one tough-ass knife fighting battleship. Of course with Barrage ammo your knife becomes a gladius.