775640 is just common 1/4" rubber fuel hose.
Any good quality reinforced fuel hose should work just fine. I buy mine from Stens, I get several years out of it, longer if I bother to put it in a sleeve to keep the UV light off it. I wasn't getting more than a year or two from the marine hose I was buying.
I cut a length of black vinyl tubing, the stuff they use to cover air lines on heavy trucks and slide that over my fuel hose on both sides of the bulb. I also buy crimp clamps vs using worm clamps that get caught on everything in the boat or cut into the hose. If I have to use worm clamps I'll cut a piece of either paper or plastic to go between the clamp and the hose so the clamp doesn't cut into the hose. The pinch type clamps though work best.
Avoid the gray vinyl hose some aftermarket marine dealers sell, it'll hard up and crack in short order both UV and ethanol tear that stuff up fast. The size of the fuel hose between the motor and tank is really determined by the size of the barbs on each end, if your quick disconnects have 1/4" barbs, use 1/4" hose, if they have 5/16" barbs, then use 5/16" hose. it'll make no difference in the end. The same if they're 3/8".
The diameter of the hose won't matter just so long as it fits without any leaks.
1/4" line though is sufficient flow wise for all but the highest hp, highest performance motors.
Any motor most of us will have on a tin boat will only require 1/4" line to be able to draw enough fuel.