This maybe more than you had in mind, but this is what I did to my 87 258 to help performance. I installed a holley 470 TA 4 barrel, offy intake, comp cam, rollor rockers, 4.0 head, header, hei distributer, MSD, and 4:10 gears. Needless to say, it romps. I'm so impressed with it, I could care less about a stinlin V-8. It makes peak torque at around 1,800 rpm's, awesome on the trails, it boogies down the highway and light the tires. The holley TA 4 barrels are made for off road and will take extreme angles without flooding or fuel starvation. I've had a lot of jeep I-6's over the years, but this is the first one that I've built like this, truely impressive. The 258 in an awesome engine with it's lowend torque, any upgrade just makes it better.
1987 wrangler, 258 I-6, 5-speed.
2007 liberty sport 4X4, automatic
2009 ford ranger 4x4 FX4 OFF/ROAD, 5-speed