If you were going to try the 3.5 5 cylinder Colorado engine, you would be better off going for the 4.5 6 cylinder from the Trailblazer/Envoy. That 5 cylinder is underpowered, even compared to the old 4 cylider S10. I've measured the 4.2 (Parents have an Envoy), and it measures pretty close overall to the 216/235. I think it'ld be worth it to get the extra power, especially since you would have to make the same mods either way.
