The issue would be the 6 psi required to fill the float bowl. The pump is used to provide a constant fuel pressure. Gravity feed systems are prone to starve the motor for fuel in the corners and under hard acceleration.
just my 2cents

 

Here is a kit made to do just that.
http://www.maxairengineering.com/mm5/merchant.mvc?Screen=PROD&Product_Code=NO_PUMP_MOD

 

I've done it. It was a great experience. I needed the switched power supply for my radio. The most difficult part is bending a piece of 3/4" steel to 90 degrees, drilling 2 holes, and notching it for a place to mount your choke.

I can run at 93mph all day long with no pump, vented gas cap, and no other modifications. At 98mph I can run for 10 seconds. At 102mph I can run for 3 seconds before it sputters due to fuel starvation.

NO kit needed. Seriously. Don't waste your money. Vent the cap, get a $3 fuel filter, 1.5' of hose, and some clamps. It's really easy.

 

My pump failed last week so I am now pumpless. I am actually getting too much fuel at certain speeds, so the carb needs some fine tuning.