'83 TBird Build

[gsmotorsports]

Aright well I've been looking back into things and have learned a lot so now it comes to some probly easy to answer questions that i have. I've read about tons of 347's not lasting very long. some as few as 10K miles. But is that just due to the quality of the parts used and maintenance of the engine rather than pushing the block to its limits?
I've been thinking about reliability and quality as well too. Would a 347 really be that smart of a build for a reliable street racer? I dont see myself driving my Bird nicely with 450 ponies under the hood and thats also a lot of mouths to feed. I have a great sound system in my car as well so I love to just go on drives. But I dont even see a 347 getting much over 15 mpg on even the highway... Would a 306 get any better? Yes theres less displacement so theoretically it wouldnt use as much gas... right?
Basically here is what I'm getting at. Would a 347 for basically sole street use be overkill compared to a somewhat more economical 306 w/ EFI and a small turbo? I feel that the 306 would give me plenty of power for street light racing and be plenty more reliable than a 347 which may possibly only last me 10,000 miles...
Just some thoughts let me know what you guys think.
Thanks