1987 efi fuel tank in 1973 k10 question

[Mike_The_Grad]

Hey everyone, I'm doing an LS swap for a buddy of mine and decided to go with the 87 efi tank with sending unit and walbro 255 pump. My question is what do I do about the fuel tank filler neck hose size compared to the fuel tank filler connectio of the 87 efi tank? From what I read they're different sizes and after bugging my friend Google for the last hour still not any closer to a solution. Any info? Thanks.