1/4 line is a restriction to a flow of 400hp of fuel, for sure. Will you get a decent lot of fuel through it? Sure, but the pump will be working a lot harder to do so, drawing more current, and heating the fuel more as it goes.
FWIW you're better off with 1/4 feed and 5/16 return than the other way around in terms of regulator linearity and worse off in terms of outright fuel flow available to the engine.
5/16 line will flow enough fuel to make some decent power without excess restriction. On my truck I went to 3/8 feed, and used the factory 5/16 carby suction feed line for the return, ditching the factory 1/4 return line. But I have lofty goals for that thing
Outright flow depends on when the fluid breaks out of laminar flow into turbulent flow, and what that turbulent flow limit is. Adding pressure doesn't help much past that point.
Not sure what your goals are, but you don't seem to have ample valves, and if thus unless you throw money at it, it'll never be super high in horsepower, so your lines are probably fine as is.
In my recently 16v swapped 240 as mentioned above I'm planning to make around 350crank hp/300whp or so and have no plans to replace the 1/4 return line or 5/16 feed line (just cut it and inserted the pump/filter setup from a 940 in between, will upgrade the pump if required later).