Borgeson box to -71 Duster

Hi! Im going to buy a borgeson Ps box for my duster. But I cant decide should I buy it with small or large sectorshaft.
My current setup is:
-71 K-Member
-73 Disc brakes
-PS-box from 70`s, has large sectorshaft
I have all the parts to do ether way, but which would you preffer, the older smaller or the bigger...