Why hasn't anyone released a HD truck with a Turbo V8?

I would love to see the old cast iron Ford 300 (4.9L) straight six brought back, but turbocharged. Bring it up to the modern age with variable valve timing, variable ignition, 4 valves per cylinder, and direct injection. About 380 hp and 500 lb-ft at a low 2,000 or 2500 rpm would be ideal for a gasoline Super Duty.