My 70 Dart

Nice progress!

A hint for spotwelding. Make a circular motion with the mig gun. Start on the thicker piece and take no more than 2-3 seconds to complete the spot weld.

Butt welding is fine but the lap weld mentioned above will be much easier and stronger.

Filling in holes is a cinch. Just need to put some sort of backing behind the hole that wont stick. Copper,aluminum etc. I just flatten a piece of copper pipe and stick a handle to it.