Bigger tires will affect you in all gears and take away some of your get up. Whereas an o/d only affects your engine speed in o/d. O/D lets you keep the good off the line chacteristics and then keep your rpms calmer on the highway.
Old '52 chevys with their stock 216s (90 hp) ran 4.11s with 2.94 low gears, you could barely get thru an intersection before you had to shift outta low gear (but at least you could get thru the intersection without having to open the door and push it off!)
Frank mcGurk always recommended the PowerGlide rear end ratio (my favorite) 3.55 for them when their engines were modified. My experiances with early chevy lls and the later motors with 3.55 gears/early Nova size tires were all good. I could buzz along the highway at about 70 taching little over 3000 rpm with a 1.00:1.00 high gear (it certainly would get the condensation outta the oil pan!) On short 100 mile jogs it was ok, but I will admit I wouldn't want to drive coast to coast that way. It is surprising how doggy a low numerical axle ratio will make a small engine feel. 396 chevelles, 409/340 hp, and the big V8s can pull them well-but thats because they have some 200 more foot/lbs torque.
A good rule of thumb to compare stuff like that, is assuming the engine size to be your torque spec (not entirely accurate-but reasonable) and multiply it times your rear axle ratio, then compare it to other engine/axle configurations--the more the better, now multiply in the low gear ratio also and you can get a grasp on how it will come off the line when compared to others. Now you can see how 283 '55 chevys and 4.56s can run with '66 396 Chevelles w/ 3.08s (a 4.56 on a summertime Texas highway is not a pretty thing with most any motor- there is where the worth of an o/d lies). Just rule of thumb mind you.
