Putting the sending unit on our already weak fuel rail is just begging for it to crack and spray gasoline all over your hopefully not too hot engine compartment.
Most folks that tap the shrader valve use a relocate line to move the sending unit to the firewall.
http://www.arautosports.com sells the hose complete to do this.
Other option is to get a fuel pressure test fitting" from Whipple Superchargers. Then you can tap into the fuel line under the cab and keep all that crap out of sight.
And Yeah this does belong in Tech forum however, all moderators rights have been yanked due to a multitude of crybabies on board.
If you want anything out of the board talk to Keith, he is the almighty moderator.