If you want better gas mileage and cruise speeds, get a 6 cyll Nova. just sayin
I hear ya and the probability of highway travel its relatively low, so I'm inclined to run the M20. I live in the NE, which means winter is 6 months long, I don't get to put a ton of miles on my car every year. Fuel economy is not at the top of my list by any means, it's the 2800 rpm just to cruise the two-lanes that's making me hesitant. The cheapest way to remedy would be to just swap out the rear gear set for something taller, something to make the 60mph more tolerable.
If I'd just hit the jackpot, I'd have the bank to sort out a plan and do everything front to back all at once and not have to revert a change I just made haha.