there might be a few horses left on the tuning table
you could pull the motor, get her on a dyno and really dial in the jetting, plugs and timing
might be the only bang for the buck left in the motor BUT that is considering you are willing to pull the entire motor
I had the entire car at the dyno after I got it together. The Dyno results from the couple pulls they did, got me 306 Torque and 260 HP. Sadly the engine dropped the #6 cylinder so I never really did find out the whole potential of the engine, hence another reason why I was curious if there was something else I could do.. After the engine got rebuilt again, it feels like more power than 260, but I have no idea.
Going to the track at all. Start tuning it up. Chassis, Suspension, tire pressures, front end movement/lift, launch RPM changes you'll be surprised at how much can be found in basic tweaks.