Looking to make some 660s and want to purchase some triggers and dogs that would fit 7/16" rod . Having a hard time finding where to get them. Any help out there?

Look on You tube. you can cut a 330, weld on round stock and use the same dog and triggers. Just don't go over 24" they seem to flex a bit when they are that big. I bought bike spokes and added them to the trigger.

I modified a Belisle by cutting it apart and brazing new pieces in between by using a small section of 3/8" steel break line. Used the old dog and made a new trigger by replacing the old one with a piece of electric fence wire. It was simple to do and didn't take long to do.