I've had good luck with AMK. I don't know if they are always right, but they are very detailed on application and I bought from them a few times when I knew the fasteners weren't even close to original or I was missing parts completely.
They show something with flat washers in their 68 master body kit. It is labeled for the front bumper "stabilizer brackets". I'm not familiar with your assembly, so have no clue if these are correct but you may want to look if you haven't:
https://www.amkproducts.com/master-k...s&element=Body
Here are the bolts and washers that look similar to OG68's:
https://www.amkproducts.com/master-k...s&element=Body
Mike