As long as the diameter of the supply
line is sufficient to get enough
fuel to the engine at full throttle, then it should be fine. If you haven't had any trouble with the engine acting like it was
fuel starved, I wouldn't worry about it. However, if the
fuel hose(s) are more than a few years old, I would replace them with some of the new ultra-low permeability hose. The standards have been updated recently, and the new stuff is much better.
The return
line should be the same diameter as the supply
line. The vent
line for the tank is usually a bit larger.