Where to run gas tank vent line with tank moved to rear of truck?

[69gmcshorty]

wow seems like an epidemic. I have a 49-52 passenger car tank in my 69' and I am just now getting it all hooked up. I am questioning my filling and driving problems that may be what others here are having. I have the filler line and a vent line, (vent that is coming out of the tank to its own line not hooked up to the filler line.
Question: will my one vent line be ok to fill and run properly with no vapor lock? meaning will it be able to fill and drive ok sucking air in from the one vent line?