Wrong Gas Tank?

I had a new tank installed in my 70 340 swinger and when I got under it today I see 4 lines coming out of it that the old one did not have. 3 of these are plugged and the 4th has a hose on it running to the filler neck. Also, when the air temp rises, gas starts leaking out of the tank around the filler neck until I loosen the cap and then a surge of pressure exits the tank. Is this tank safe, and how do i fix the venting problem?