[motoguy128]

You can't go wrong using a larger wire size. It's a little more in materials, but will carry more current with less line losses and less voltage droop. But you really should be following the National Electric Code.

A real rpofessional would be getting materials frmo a local supply house. A simpel google search can find a dozen online sources for components, some may or may not fit in your air handler. IF you're ordering online, you have to really know what you need.

Heat strips should have and normally would have been ordered with the air handler.