on my 66 theres also a braided ground wire going from the head to the firewall,,, if the starter cranks like mad with a direct connection as in pull it and just connect it to a battery ,,then I'd say grounding issue,,, not a good situation but some times ya gotta just grind thru it allto fix the issue

 

A bad ground won't stop it from cranking. It just won't start.

How sure are you about the battery? If you are only getting weak lights then that might be a place to look again.

If you are getting no action at all then you need to check for power getting to your solonoid from the igition switch. If you are getting juice to the ignition side of the solonoid then use a jumper wire acrossthe solonoid and see if it engages and turns the starter.

I'm betting on bad connections aweak battery or both.

 

I had a 68' and had the same problem once.After changing all the parts you mentioned and pulling my hair out, this old timer overheard me in an auto parts store and told me about the "fusible link" that ford put on cars in that era. It was a wire (probably a ground) about 8" long and had a fat part in it with a fuse in the fat part. It was connected to the solenoid. Sure enough, it was blown. I couldn't tell but after getting the $2.50 new one it was obvious when giving the fat part a squeeze. The blow one was soft and the good one was hard.

good luck.