Looking to replace this hinge to a turtle deck. I would need the rivets as well. It's from 1920 or so, and the supply houses don't carry it. I think it can be repaired by a good metal guy from the inside. Any thoughts?

If you want to save the hinge the best bet is to remove the rivets. Carefully grind of the heads with a small die grinder and carefully punch them out. If the hinge is made from sheet metal (maybe 18 or 20 gauge sheet metal?) you can use the old one as a pattern and make a new one. You might try to braze it or weld it with a small wire feed welder if you can weld small on thin metal without burning it up.

Thanks, John.

Tig weld it. I'd leave it riveted on and clean it up good then weld it right there. I welded the hinges back on my tail lamp door with a tig, pretty thin stuff.

Thanks, Corey. I really would like to avoid having to taking it off, attempting to find a replacement or having to make a new one. I think the repair could be made on the inside.

If you have access to a Tig welder that's the way to go. If you plan to weld it in place be careful to have the hinge pieces in the correct place.
If the parts aren't in the correct rotation with the other hinge it might bind up on one side and wont let the lid close evenly.

Yup. I agree John. Will tell my metal guy when I bring the deck over. Always learning stuff I could never had possibly imagined.