The 4.3 will give you some room to work on it and won't be so jammed in there.
My 2-door S-10 Blazer (don't have it anymore) had that engine and was rated at 190 HP and something like 235 lb-ft of torque by then (my model year) and had a pretty good, useful torque curve with the 4-speed automatic. The Blazer, even the 2-door, wasn't a particularly light vehicle and the Vortec pulled it along very nicely, and still does with the full-sized Silverado base model "work trucks."
In God we trust.
All others bring data.
'02 Sport, soft top, 6 cylinder
5 speed manual, 4" lift, 33.5" tires