so i'm rebuilding my original 1970 340

i want to have the lightest rotating assembly possible , forged crank h beam or I beam rods and forged pistons , don't want a speed demon more for highway driving ,maybe a road course once in a while \guess i'm going to go roller cam on this build going to use the hughes rockers and morel lifters . not sure which heads and cam to get
Who makes the lightest crank rods and pistons these days also want the best gas mileage possible , i got around 22 mpg with my last 340 but that was stolen
Open to any and all suggestions

If you want gas mileage, 2.94 rear gears are your friend. Stock '69 318 with an added 4 bbl in a B body did 20 mpg. And not totally babying it either.

Enjoy . . .