Run a 12 from the cell to the pump and a 10 all the way to the regulator then 8's from the regulator to the carb. Also run a 10 return line if it's a bypass regulator.
Two -8's do not equal the same flow as -16. The reason for needing a bigger line between the cell and pump is it's a suction line not pressure. You have a fuel pump,not a fuel suction,gravity supplies the pump. Fuel and fire are two areas in making horsepower that you don't want a weak link.my Y doesn't look bad. I have it all underneath the car and you can't see it. Looks real good.
The Y fitting is like 35$ though.
2 8's is like 16an so its enough fuel. If i can find someone who can tig weld alum, then i'll put some 12an on there and run 2 a1000 pumps.
That's my philosophy. Do it right the first time and you'll save money in the long run. Cost twice as much having to do it twice.You will know if its not enough.........but I would want to find out the way you would if its too small.
Fix it now and dont worry....just my thoughts.