Like Kevin, I once built up a Fiat 124 spider 1600cc motor, stock hp about 90. I swapped the progressive 2bbl weber for a pair of 40IDF weber 2bbls on a tuned length intake, 40-80-80-40 cams, headers, bigger valves, and some port work, and had a calculated 150hp, but it was a dog below 4000rpms, after which it was a screaming rocket up to 7500rpms, and it was LOUD, and very very hard to start in the cold. I only got about a 10ftlb increase in torque, but at 1500rpms higher than stock.

I restate again, doubly redundantly, the most bang for the buck power increase I've ever done is swap in a starquest turbo motor into a carb 2.6 truck.

Were you plowing in 4wd lo range? I'd consider a poly water tank for ballast and studded tires...