Cuda won't start and have tried multiple avenues. Need help!

Red63440 said

You should also have a ground cable that runs from the rear of the right head that goes to the body. These were put on prior to painting at the factory to secure a good ground but the previous owner may have installed it after painting, check this connection...it should be attached with a sheet metal bolt and a toothed washer.
IF you are using an aluminum intake and have the ground from the battery connected to an intake bolt check it closely, the bolt and intake are dis-similar materials and are prone to corrosion.

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I checked all the cables and went ahead and cleaned them all and the battery terminals while I was at it. The round on the body that you mentioned was covered in paint. There was only a very small sliver of metal shining through. I cleaned that up so there was a good metal to metal contact there. The car started up and has continued to start up since I fixed that.

Thank you very much and everyone else here for their help and wisdom! Looking back at it now seems so obvious, but it's great knowledge to have going forward.