What Gear And Carrier In My Javelin?

[do it again]

Hi,
I recently put a used rear end in my 74 javelin from a javelin built to drag race. Someone built it with moser axles and it is supposed to be limited slip and has a four link set up welded on. Also, when I drove it I can only get to about 70mph! What gearing would only wind that far?
The motor is a built 304, the trans is a stock borg warner three speed.
I know its a dana 20 by the round housing.
The questions are how to tell if it is limited slip, what gear is in it,and what gear I need for street/cruising use. I need the info so I can find a different ring and pinion set. Thank You !