disclaimer: I have little understanding of gear ratios and their relation to rpms.
It makes sense to me that with 4.10 differential and a performance chip (like Conforti) raising your rev limit to 7k your would be able to reach speed higher than 54mph.
Theoretically, wouldn't giving yourself 500 more rev each gear and thus extending the mph each gear could reach?
Let me know if my logic makes any sense.