I never noticed much difference due to gearing, but I have with what engine is ahead of the trans. I have a 98 Formula with the LS1 and 4L60E pushing 2.73 gears. There is also the 70 GTO that used to have 2.93 gears and it had both the Th400 3 speed and 2004R OD behind its 455. Either one of those cars rolls along no problem at 75-80mph, the only difference is cruise RPM and of course the 455 could pass or go up hills much easier than the LS1 can at 1700 rpm.
That might be part of the thing you are noticing. The cruise RPM with OD is pretty low. Your typical carbed sbc wont be able to pull a car as easily at 1500 rpm as a later EFI engine, or the 455 that is making 450-500ftlbs right about there. Lots of things come into play when cruising a low RPM like that, not the least of which is carb signal, and your average sbc doesnt have much compared to the larger Pontiac, so it wont run quite as well that low. EFI takes all of that out of the equation and then you are left with how much torque it makes there. How much grunt it has depends on the bore, stroke, and cam timing, plus a few other variables.
So if there are other issues, like the brakes are dragging, the alignment is off, the wheel bearings need repacked/replaced, or the tires are under inflated then it will feel like the 3 speed car is quite a bit more sluggish. One of my 11-12 second cars picked up .6 in the 1/4 by simply repacking the wheel bearings, truing the front rotors and rear drums, and giving it an alignment. That kind of stuff makes a huge difference.
Its something other than the gearing that is making the difference in your mind.