Been thinking about it.... Not sure on a clear winner.
SP2P or Performer or cast iron intake + TQ. But I would run the TQ.
That vehicle is a heavy mother with perfect brick like aerodynamics. You drive that pretty far each day. Mileage has got to be rough. I think a different ride is in order. If it has to be an old one, I'd look to an A with a small /6 or small V8 & an O.D. Transmission.