Don't cut the fuel pick up screens leave them stock length so you can still have a reserve.

To do the mod
1) Remove the petcock
2) Take petcock apart
3) Clean filters
4) Remove small set screw that holds fuel selector in
5) Remove selector, being careful not to loose the spring behind it
6) with the long tab & arrow facing down, mark the existing channel to the left another 1/4 turn (should allow selector to spin to the right from "ON" to fuel
7) Grind out the marked channel with a dremel to match the existing set screw channel until the selector with the set screw in will turn to "Fuel"
use carb cleaner or berrymans to get all shavings off and reinstall it.

Once the selector is on "Fuel it will flow both the regular & reserve pick ups

You can use the fuel selector as, on (1 long pick up), reserve (1 short pick up), or Fuel which is both on & reserve at the same time.