Hi!
I agree with watkins....
The clunk should never fall forward in a fuel tank!!! If it does it will get stuck there. Thats why Sullivan and other fuel-tank manufacturers recommends soldering a piece of brass tube to the clunk...so that the fuelline can't bend forward....
I haven't seen a tank that has space enough up-front for the fuelline and clunk bending forward...and then retake its position again.
The clunk and fuel in a fuel tank isn't constantly swooshing around inside the tank... they are both more or less in a fixed position only moving slightly depending on the G-forces.
When you dive down with an airplane you are most of the time accelerating down so the fuel will stay at the back of the tank ...not falling forward!

Regards!
Jan K
Sweden