get your ignition system checked, if timing is off, or your loosing voltage somewhere then that can cause the hesitation.also when was the last time you changed your fuel filter? as far as old verses new, properly tuned and maintained carbs will go almost shot for shot with an injected setup. also less prone to random electrical issues.
In my car once it had the hesitation on hard acceleration, then it eventually would stop running at a certain point in the throttle while driving down the road, had my whole fuel, vacuume and ignition systems checked, and it was my old point gaps in the distributor. after a couple parts and redialing in the timming, it runs like a champ.
