For what it's worth, When I had the 1.6L 16V in the tracker I never needed or wanted more power below 3000 rpm, it was above that when i couldn't get launched hard enough or keep the wheel speed up. A lot of that had to do with gearing but you gear for the power you have. Campbells have had good luck with their turbo ecotec pro mod buggy. Only every once in a while do you see them struggle from a lack of grunt down low.
A 4.3L swap would be a lot cheaper if I were to guess.
Let us know what you plan to do!