The TBI 454's are both cam choked, and the heads don't flow well either. Since it's a manual I'm tempted to say cam swap because you can go with a more aggressive cam without having as much stalling and tuning issues. The hard part with that would be getting it tuned right, not sure how hard that is on the TBI systems. I think you have to have a new eeprom based chip burned for it.
There are a lot of little things you can do like opening up the intake and exhaust, tuning, etc... that will help a little, but to make it 'fast,' -which is a relative term- you'd probably need heads and cam, or some manner of forced induction.
That's my take on it anyway.