Fuel / Gas Sending unit question

Putting in a new Fuel/Gas Sending unit in my 69 Dart when I replace the gas tank. I have been looking at them on Ebay, VansAuto, Rock Auto etc and have a couple questions for those who have been there/done that:

• Stainless steel or Zinc unit?
• Plastic or Brass float?
• Should there be a strainer sock or not? Pros/cons?
• Does the 69 Abody have a return line on the unit or not? Different sellers show with and without.

Thanks for any help...