Those low compression heads are not very good and you don't say what kind of compression you have, BUT at 92mph and 3200lbs you show to only be making 200hp. Even with those heads you should be making more than that. With a 29.5 tire I would stay with the 4.56s. If you are only going through at 5000 you aren't going to like the 4.10s. Did you put a comp recommended spring on the heads? Is this a drag only car? Are you spinning on take off? Gas set up? What kink of timing, locked or not? What MSD ignition box? Many possibilities as to what could be wrong. We will just have to wade through until it shows up.
Curtis