350 TBI unit capability

so i'm going to run Buick 350 V8 out of '70 Skylark that was cammed, dual plane carb intake, longtubes installed before i got the motor so don't know the specs.
this setup is for keeping best MPG but don't want to sacrifice much power, probably like we all do :rolleye:
there is also some budget to keep so my question is if 350 GM TBI unit with injector spacer will handle like 250-300HP to the crank?
to control fueling and spark i run eighter Megasquirt or Speeduino with WB so it will be finetuned easily.