So i replaces my stocker with a yellow top. I want to run a second battery as well, unisolated. I was advised against using the stock one with the yellow top. Ive been seeing builds where people do though. Are there issues here that i teally need to be concerned with or not? I believe the stock is an AC. Delco. Eventually when cag allows it i will match batteries but would this be ok for now?

In your case just run what you can afford. I ran 3k daily in my truck before adding batteries to run 6k. Those trucks have a big battery and decent alternator.