I'm in the process of putting an approximately 480 crank HP LSx motor (LQ9, 317 heads, 10:1 compression, 232/244 .621"/.604" lift, 850 carb, victor Jr, 1 7/8 long tubes) into an S10.

I'd like to do the fuel system at this time, too. I'll be running a 15 gallon fuel cell in the bed.
I want to run a Holley red or blue pump (leaning towards the red pump so I don't need to plumb a return line).

I want to order my fittings and fuel line. Should I go with 6AN or 8AN line for this truck?

 

Anybody?
Would it hurt to run -8an (maybe to leave room to grow?) because it won't really cost much more to design the system from scratch.

 

The -8AN should be fine.

 

I figured bigger wouldn't hurt and would ensure I have room to grow in the future. Thanks.

 

I had to make that choice and I went with -6. I wish now that I hadn't. -8 would have me covered for this years plans.
On a similar note, a return line isn't such a bad idea. I was forced into that due to the fuel heating in the single supply line. You'll have the option of routing your fuel lines wherever you wish however within the confines of a more or less stock 3rd gen chassis, the lines run very close to the exhaust. Sitting in the staging lanes at the drag strip, with the fuel more or less at a standstill, causes some vapour issues. Something I'm taking care of this year with the Holley Blue pump and return style regulator. There's a measure of circulation and I'm hoping no vapour lock.

 

Thanks for the advice. This is in a 2nd Gen s10.

I haven't decided if I want to run the blue with a return regulator or just the red without one.

 

-6 would be sufficient, but like said, doesn't leave much room for growth. I was running -6 on my 415 RWHP setup, added -8 when I converted to E85 and used the existing -6 for the return (along with an intake change then dyno'd 435 RWHP).

Sounds like you're building a drag race setup. Personally, I think regulating with a return is always a good idea. What carb are you running? Some Holleys now have fittings on both sides of each bowl so you can run supply to one side and return with reg on the other side so the needle/seat is bleeding off the fuel it needs from the flow going by. Keeps the fuel going into the carb (and the carb itself) cooler.