IF you to the cam, together with switching to 1.94 heads, a new intake manifold, port the heads and manifold, new carb, add headers with crossover pipe and dual exhaust, it will wake up and tow much better.
But, I would do that to a 454 instead and drop it in, instead of putting that work into the 350. Old 454's aren't expensive and rebuilding a 454 doesn't cost much more than rebuilding a 350.
If you put that together with an axle gearing change to 4.56, you will have a great tow vehicle, provided you are fine with crusing around 55mph on the freeway.