need a little help on building my rear

So the time has finally come for me to get my rear here the deal I'm going to be ordering a complete rear end from moser I'm getting the Moser 60 Built to Order rear but my issue is what differential should i go with my car is a 72 demon 440 stroker 4 speed car that's gonna see the track as well as the street i just want to get a differential that will work for both any help would be appreciated thank you ...here is the link to the order fourm on my options http://www.moserengineering.com/complete-rear-end-assemblies/12-bolt-part-number-configurator-1.html