I think mid 13's is a bit optimistic for that combination. Mid to low 14's is more realistic IMHO. One thing you have to keep in mind is that dyno horsepower horsepower numbers are corrected to 50ﾟF at sea level. Unless you were racing in that kind of density altitude, the car will be slower than the dyno and and the calculator indicate that it will be. Have you had the car on an accurate scale, or are you using an estimate. Sometimes these cars are heavier than we think.

Most untested street cars that I have brought to the drag strip for the 1st time run about a second slower than they are ultimately capable of with with dialing in.

Most of that 1 second gain comes from things that have already been talked about on this thread. Making sure that all the butterflies are opening all the way. Verify the timing mark and the timing. Take the spare and anything heavy out of the trunk. Don't have a full tank of gas. Make sure that you have adequate fuel pressure and fuel delivery through the entire pass.Experiment with launch RPM, shift RPM, tire pressure, different timing, different air fuel ratio. Sometimes it takes different gears or converter to get it where it should be. Also if the car has been street driven a lot, the backsides of the valves could be carboned up hindering flow. If you are running it through the mufflers, try yncorkung it. Does have a big fan on it with no fan clutch? That will slow it down. It's usually a bunch of little things and not one big thing. Are you running headers, or exhaust manifold's? Slicks or street tires?
Good luck, enjoy the process.