What is your trap speed? These cars should have enough power to run in the mid 12s stock even with sh*t rear suspension (which they have for drag racing) and hard tires.
Is the track launch pad surface smooth concrete? Or Asphalt?
Without a LSD, racing tires, some working suspension, and track prep, you're never going to get a hard launch. Good news is your clutch and half-shafts will last a lot longer
If none of those things are going to improve you should be able to run much quicker just soft-launching the car and driving the piss out of it.
Good on you for drag racing a manual trans car, there aren't many of us bad-ass mofos out there