Do not change the fuel system. This system was carefully and thoroughly flight-tested at all attitudes and works very well as per plans. Several builders have asked if they could convert the fuel system to a both on" situation. Absolutely not! Both fuel tanks feeding the carb together will only work on a gravity system. The Long-EZ does not have enough fuel "head" to use a gravity system. Therefore we use a pumped system. That is, the primary pump is a mechanical, engine driven pump, backed up by an electrical boost pump. This is similar to most low wing airplanes, Grumman Tigers, Cherokees etc.
If you try to pump fuel out of two tanks at the same time, it can draw from one tank only, until it is dry. Then you will get air, and in spite of having one tank almost full of gas, you will flame out and have to land because of fuel starvation.
Be very careful of fuel systems, they must be absolutely fool proof in order to work reliably and consistently.