imho running it on the limiter is probably worse than letting it turn past 7k. i understand you not wanting to turn it fast but banging on the crank with the limiter isn't a good idea either. peak HP at 5800 sounds a little slow i would think it would peak higher. i know you've had problems with wheelstands on launch did you get that sorted? if i recall correctly my car goes through around 7300 160ish MPH. that's with a 4.10 axle, 8" ATI Treemaster and 14x32 goodyears. i figure the engine is making around 600HP. if that engine is making over 700HP your numbers are off. as mentioned the first thing i would do is get a good converter in the car. i would expect my tires to grow more than yours but given the >700HP you should be running over 160MPH. if the engine does in fact peak that low and you want to turn it slower you may end up having to change the axle ratio.