Nice looking Challenger.
If it is the timing chain, it’s not too bad to replace. You have nice weather, so it wouldn’t be too bad. Make sure to take plenty of pictures of where everything goes and the alignment.
I’ve seen this happen, double check your fuel filter is not installed backwards.
Don’t give up, stand back and give it a rest for awhile. You sound like me back when I was working on my Challenger back in the 70s. It’s a 318 that wouldn’t start, I popped the distributor cap, the rotor wasn’t turning. It was a nylon gear on the distributor that snapped off. Post some pictures...