Engines would have been cast 3-9 months ahead of a car build. So I wouldn't think a date coded block that is after the build date of your car is going to matter much unless it is a warrenty block. But then again, I don't know the # matching rules very well either.
You can nail down the car build date with the vin. Google vin decoders and try a few. Also, a build sheet gives you becoup more info than a fender tag would. With the build sheet you could always have a new tag created.