looking for a complete tbi or vortec motor- have questions

[68c10owner]

I want to upgrade my 84 burban to a fuel injected motor. What are the tbi motors going for? what about the vortecs? what kind of fuel mileage do the tbi motrs give? I used to have a truck with a vortec 305 and it was a good running truck and got decent mileage. I just want something for more performance and fuel economy than my 84 electronic carb 350. I also want to eliminate some smog stuff and I know the later motors did`nt have as much as my 84 does. at least my old vortec 305 did`nt have much. thanks for any info.