Allow me to just name drop for a moment and say that [MENTION=148218]JZiggy[/MENTION] and [MENTION=665220]Pyral[/MENTION] make super solid points.
I will say that, many moons ago when I was 18, I had purchased my first vehicle. It was a 1996 base model, 2WD auto with the 2.7L. I f’ing loved that thing and I miss it almost everyday. It was literally completely stock. Zero modifications. Low mileage, I wrecked it. But now that I’ve owned my 3.4L for almost 9 years, I will say that they are indeed comparable. The only time I noticed any difference with the 2.7 was, as previously mentioned, merging onto the highway. Aside from that, I don’t really recall any speed issues. Plus, I’m not going for “speed” in a 3rd gen 4Runner. Like what? Gas mileage is definitely similar as well so no noticeable differences in that department. Less maintenance due to timing chains and whatnot is SUPER nice for sure. If it were me, I’d say pull the trigger on it. 2.7 or 3.4 doesn’t matter to me. If it meets the criteria of: 3rd gen, overall in good mechanical and physical shape, has been taken care of, then why not? If I could do it over again, I’d get the same truck I had, just with a 5-speed manual trans and 4WD. But those were rare in the 2.7 from my understanding