I don't know how I've survived all these years with the 8.7 0-60 I have in my Avalanche. But I will say I rarely ever have to race it to get on the highway.
It was more true back in the old days than today, but yeah, that's a benefit of pushrod over DOHC. The GM Pushrods engines, even the V6es, made really good torque at low RPM but ran out of breath at high RPM.
It's a really unfortunate side effect that the boy-racer craze from the 1990s robbed us of some perfectly good engine designs because enthusiasts wanted engines that rev to eleventy even though the typical family hauler would be more efficient and more relaxed with a torquey pushrod. It's why the first few generations of GM 3-row crossovers (Traverse, Outlook, Acadia) are all absolute pigs on highway MPG. They constantly have to shift out of top gear to spin up when torque is needed, while pushrod wouldn't have needed to as much. It's telling that a Tahoe and a Traverse were capable of similar highway MPGs
I don't know if the 4.3 V6 would have physically fit in the Traverse, but I bet it would have had better efficiency and similar real-world performance to the 3.6
Way back in the day when GM was putting out the giant 6, 7, and 8 liter engines, those were the ones that were all torque at low RPM. Even my weezy old 307 puts out most of its 250 lb-ft from 1,000 - 3,000 rpm. Red line was 5,000 rpm. It's not fast, but it will glide effortlessly up to 60 right along at traffic's pace only using 3 gears.