Thank you, Hotrod Lincoln. I was hoping to not modify the engine, but still, from what you said, the unmodified 250 is the best option. As with so many things, the in-between is a good choice. In this case, it might be my best choice of balancing power with efficiency, at least as far as an I-6 is concerned.
As for the V8 engines, I bet they continue the trend of increasingly more power/less efficient. Would you say the smallest V8 is more powerful and more fuel-hungry than the 292 I-6?
Thanks.
Steve.