1994-1995 iron V10 camshaft specs might be a clue to the best fuel economy.

In their SAE paper Chrysler engineers proudly stated that this new bigger ”towing” engine was more than 10% better BSFC than the GM 454 V8

Since there has been a clear trend from 180 on up to 207+ coolant temperatures think about experimenting there.
Since there is good older evidence that 140 - 160 is best for peak high rpm power,
those higher coolant temps were adopted to increase fuel economy at lower cruise rpms.

5.7 engine’s variable valve timing would allow “dialing in” the highest tolerable dynamic compression ratio.
A “de-stroked” 5.7 with a longer connecting rod would have “superior leverage” with a less torque robbing rod to crank angle.