What does an economic GM 5.3L build look like?

[Solarpowered]

Hi all, new here. It's time for me to replace the worn out 350 in my 1987 Silverado. I don't wish to hurt it's performance as a half ton truck, so I've decided to improve it somewhat by converting to the newer and more advanced 5.3L V8.

I'm going to have an engine built for it, by a qualified builder. So why not have him build it to be as economical as possible? While also modifying a few other things for fuel economy.

Below are my (rough) ideas so far, you guys can pick through and tell me where I've messed up. Looking at what I've got on this list, do you think I could see a 5mpg increase over the old 5.7L 350? That's my goal here. To notably improve economy and increase this engine's power output a bit.

More efficient GM 5.3L

Lighter connecting rods
Better roller rocker arms. Aluminum
Lighter crankshaft? Aluminum
Good oil cooler with thermostat
Good trans cooler with thermostat
Electric water pump
Electric cooling fan
Electric power steering?
More efficient alternator
High flow oil pump with bigger better filtration system
6 speed automatic transmission (6l80e)
Lighter pistons
Lighter flywheel
Aluminum or carbon fiber driveshaft
Long tube headers and good exhaust system
Floating pin pistons
Internally balanced. Meaning the crank itself is balanced - May negate need for harmonic balancer
Better pistons and rings somehow?
Heads, cam, and intake might have some effect on fuel efficiency
Long tube headers and matching exhaust
Convert to timing belt instead of chain. Less rotating mass.
E3 Spark plugs