Smooth out the Sparrow troughs on the underside: airflow in that area is REALLY important on the F-14 (the AIM-54s screwed it up so badly that 4 x Sparrows on the belly were often chosen where long-endurance was more important than engagement range).
I'd hesitate about shortening the beaver tail: you might get increased base drag that negates the benefit.
Lengthening it on the other hand, and making it a smoothly tapered shape, might actually reduce profile drag though....
A single fin is definately a good idea IF you don't need high-alpha maneuverability.
It all really depends on the format of your race: if it's a long-distance straight-line exercise then all these things will make a difference. If it's a pylon-race-on-steroids though, you might want to retain that high-alpha capability since there's not much point going like a bat out of hell down the straights if your turn radius around the pylon sucks. If the distance is long, then the Tomcat's high internal fuel fraction will count in it's favour, but if it's short, then you're just dragging empty tankage around with no benefit.
If it is a pylon race then the F-14 (or any swing-winger) would be a very keen choice, given it's large speed range. In fact, if it's a shortish range pylon race, I might be inclined to enter a cleaned-up MiG-23, given it's acceleration....
