Intank pump and need for return line

At 45 psi? I'd say Yes. Your carb will only need 5-6psi. Is your regulator up to the task? When I ask Aeromotive on running an 60psi with a carb (with plans for EFI later) they stated you need a special or multiple regulator for that much return although I found folks doing it with one, lesser regulator and reporting no issues. Your going to want a 3/8 or 1/2 return.