Lol... I hear you there. So, no headers, aftermarket intake, or other parts that would "stand out" to a judge as not being factory?
I asked because I struggled for a few years with my '69. It's too modified to show as stock, not modified enough to compete with cars with over the top paint, blowers sticking through the hood, etc.
Then one year I actually read the ISCA rule book and found a class that seemed to fit the car pretty well. "Competition Stock". For the last couple of years now I've explicitly requested that class on check in. (You do have to ask.) When the official checks the rule book, he sees that the car indeed qualifies for that class and puts me in it.
I've earned trophies every year since I started doing that.
So - it'd be a good idea to spend a little time looking at the ISCA rules to see if there's a class your car fits really well into.