Do you know where the engine makes peak power? What is the redline for the engine? Gear changes are a little hard to predict in a drag car with a torque converter since the converter slip changes at the same time. 4:11 to 5.0 is a big change. Racers usually only go one step or two steps at a time but if you have a high RPM engine and you need to move the RPM up a bunch then that change will do it.