2uzfe almost ready for a rebuild... help with choices

[rotarex]

hey guys have not been on for a while.
got a 2002 Tundra 4x4 AC. 320,000 kms on the engine, fuel consumption went from 720/ tank when it was 160,000 kms and now i get 520/ tank.

now i do have a few leaks in the exhaust but i started loosing MPG way before that, even tho everything is maintained, truck also dont got the power it had when i first got it

so when i go for a rebuild i would like to achieve maximum power without increasing gas mileage or get better gas mileage

on top of
headders-catback
ecu
Lighten pulleys (not to sure if these do increase mpg and free up power)

i would like to achieve 350 BHP at the crank so about 290 WHP
thats 85.5 hp over stock WHP

so the question is, what engine machining is needed ?
im thinking a full engine machining like this
https://www.youtube.com/watch?v=UzCVxvygrxw

 

[XR8tt]

Fix exhaust, replace 02 sensors and service ignition system..
More compression will help efficiency..
Think about forged assembly if going forced induction latter ??
Replace coolant and inlet temp sensors at that miles..

 

[rotarex]

rite now i don't want to waste much money in the fixing as in a few months a full rebuild will be done, i might just patch exhaust again.

i am planning on rods and piston from lex. but don't if i should stick with stock compression ratio or go a bit higher

correct me if im wrong, if i go a bit higher on the compression ratio i can gain a bit of power with out stepping up to a higher Octane fuel and at the same time a supercharger can work with this higher compression when the budget is good later on ?

 

[XR8tt]

Yes leaks in exhaust esp around sensors can play havoc with fuel consumption..
Yes with forged assembly even with higher compression a blower can be used .. Just makes tune more critical, 4 valve engines can get away with it..
Thermostat is another if engine runs too cold..