A few things to remember all on this subject:
1. Somebody mentioned to bend the fuel sender to read more correctly - this is good.
2. Also bend the pickup to make it about 1/4" off the bottom of the tank. Otherwise you will have 2 or 3 gallons unusable fuel in the tank.
3. Put vaseline on the gasket (both sides) before you try and tighten it down. Makes the job really easy to drive the eared collar home.
4. Run a ground wire between the tank lip (drill only on the very outer edge of the seam or you will be accidentally venting your tank) and the car body adjacent to the fuel sender.
5. Grounds should be cleaned down to bare metal, then a ring type crimp stakon used on the wire. After it is all buttoned up and connections are tight spray the connections with a rust type paint (tremclad, krylon etc). This prevents the connections from ever corroding.