Replacing whole fuel kit?

No problems on the 440, and you may be able to get 3/8" into the stock clips under the car. No way with 1/2". Besides, the line into the tank will still be 5/16". If you go to the 3/8" line, then buy a 5/16" to 3/8" adapter to go at the tank to transition the hose sizes. You may have to buy a 3/8" hose fitting into the fuel pump too.

If you are changing out the line, the clips under the car may need replacing. You can probably get them from Inline Tube (or maybe Van's) as kits for your specific car. Check the ones under first to see if they are rusted badly.