The NHRA rule book page 249 gives you general rules on venting and fire wall protection from the driver compartment. In general one should always mount the fuel cell in such a manor that permits gravity feeding to the fuel pump and the pump should always be mounted behind and below the fuel cell as much as clearance permits for safety from rear hazard. The cell if mounted below the trunk floor needs to have .035" sheet metal protection below the cell. Always use the rule book of the race body you race in to be sure that all safety rules are followed. The pump being forced fed under acceleration can be a big deal if your hot rod is very fast. If you mount to far behind the cell, fuel will run to the front of your cell away from the pump and starve it for fuel on long decell conditions. This should be avoided as well. G force on liquid at 1 G will go on a 45 degree angle from level in that condition. The pump would like to be in the fuel in that condition if rear mounted. under decell the fuel goes forward on a 45 deg if decell is one G. The closer you, to an extent mount the pump to the back side of the cell and below it the less starvation that will take place under decell. This should give you some guidelines to start the thought process and mock up of your new fuel system.