how big of fuel line do i need

5/16" is all most will ever need. No need to go nutzzz with a 3/8 line front to back. My father runs his 67 Satellite pretty damn hard, its a Stroked out 440 big block running a 900CFM carb and he has never had a "fuel starvation" problem. I would not worry about it. Have fun and put the $$ elsewhere. :)