What you've got is likely a stock gear-stack with a stock R/P. I'm supposing that your tires are 185/65R15s, but I don't know for sure. If this is what you have, you'd be turning about 3500 RPM at 70 MPH. If that is the case, this is what you have:
If you are happy with the final drive (.89/4.12) you could use a non-stock mainshaft (1st and 2nd gears) with a 3.44 R/P, and a short 3rd and 4th. Every single gear in this box would be non-stock, but I happen to know somebody with a used but nice custom 3.10/2.07 mainshaft that was just taken out.
This 4-speed has very nearly the same final drive as what you have, but it's a lot tighter spacing between gears. Of course, nothing comes for free, and you'd give up the drag-racing first gear:
... and here they are on top of each other:
The blue is what you have, the red is the closer gearstack. Somebody might have a better idea, but that's as good as I know how to get it on a Sunday afternoon.
